FULL PRODUCT VERSION :
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b81, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows XP, SP 1
Microsoft Windows 2000 [Verze 5.00.2195], SP 4
Microsoft Windows 2000 [Verze 5.00.2195], SP 2

EXTRA RELEVANT SYSTEM CONFIGURATION :
Classes are compilet for Java 1.1

A DESCRIPTION OF THE PROBLEM :
When appliaction loads from WWW server, any classes are loaded OK.
After sucesfull login into application, the application continue to load classes and then (after any time) is exception thrown.

REGRESSION. Last worked in version mustang

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
 1) Install full jdk-6-beta2-bin-b81-windows-i586-20_apr_2006.exe
  (tested with previous snapshot of jdk-6-beta2 and with jre-6-beta2-bin-b81 too)
 2) run "http://www.gapo.cz/chem/fnol_okb.html"
 3) after login dialog display, login as 'demo with password 'demo'

 
Here's the message from the Java console
----------------------------------------
Java Plug-in 1.6.0-beta2
Using JRE version 1.6.0-beta2 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\terber


----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
l: dump classloader list
m: print memory usage
o: trigger logging
p: reload proxy configuration
q: hide console
r: reload policy configuration
s: dump system and deployment properties
t: dump thread list
v: dump thread stack
x: clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------

Trace level set to 5: all ... completed.
Trace level set to 5: all ... completed.
network: Downloading resource: http://www.gapo.cz/chem/lib/rsysrtm.jar
Content-Length: 1 811 634
Content-Encoding: null
network: Wrote URL http://www.gapo.cz/chem/lib/rsysrtm.jar to File C:\Documents and Settings\terber\Data aplikací\Sun\Java\Deployment\cache\6.0\29\5a52b25d-63840575-temp
security: Accessing keys and certificate in Mozilla user profile: C:\Documents and Settings\terber\Data aplikac?­\Mozilla\Profiles\default\710suisb.slt
security: JSS package is not found
security: Loading Root CA certificates from C:\PROGRA~1\Java\JRE16~1.0\lib\security\cacerts
security: Loaded Root CA certificates from C:\PROGRA~1\Java\JRE16~1.0\lib\security\cacerts
security: Loading Deployment certificates from C:\Documents and Settings\terber\Data aplikací\Sun\Java\Deployment\security\trusted.certs
security: Loaded Deployment certificates from C:\Documents and Settings\terber\Data aplikací\Sun\Java\Deployment\security\trusted.certs
security: Loading certificates from Deployment session certificate store
security: Loaded certificates from Deployment session certificate store
security: Validate the certificate chain using CertPath API
security: Obtain certificate collection in Root CA certificate store
security: Obtain certificate collection in Root CA certificate store
security: The CRL support is disabled
security: The OCSP support is disabled
security: No timestamping info available
security: Checking if certificate is in Deployment denied certificate store
security: Checking if certificate is in Deployment permanent certificate store

  RTsSystem Applet: Initialization Begin

RTsSystem v. 1.37.0, build 10
  RTsSystem Applet: Initialized
  RTsSystem Applet started
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Cache entry found [url: http://www.gapo.cz/chem/lib/rsysjce.jar, version: null]
network: Connecting http://www.gapo.cz/chem/lib/rsysjce.jar with proxy=DIRECT
network: Connecting http://www.gapo.cz/chem/lib/rsysjce.jar with cookie "GWeb!system=k9ESwMI; JSESSIONID=3E9E9FA335A44AC33D26CF1764EAB999"
network: ResponseCode for http://www.gapo.cz/chem/lib/rsysjce.jar : 200
network: Encoding for http://www.gapo.cz/chem/lib/rsysjce.jar : null
network: Disconnect connection to http://www.gapo.cz/chem/lib/rsysjce.jar
network: Connecting http://www.gapo.cz/chem/lib/rsysjce.jar with proxy=DIRECT
network: Connecting http://www.gapo.cz/chem/lib/rsysjce.jar with cookie "GWeb!system=k9ESwMI; JSESSIONID=3E9E9FA335A44AC33D26CF1764EAB999"
network: Downloading resource: http://www.gapo.cz/chem/lib/rsysjce.jar
Content-Length: 1 138 234
Content-Encoding: null
network: Wrote URL http://www.gapo.cz/chem/lib/rsysjce.jar to File C:\Documents and Settings\terber\Data aplikací\Sun\Java\Deployment\cache\6.0\51\346548b3-54b778dd-temp
security: Loading certificates from Deployment session certificate store
security: Loaded certificates from Deployment session certificate store
security: Validate the certificate chain using CertPath API
security: Obtain certificate collection in Root CA certificate store
security: Obtain certificate collection in Root CA certificate store
security: The CRL support is disabled
security: The OCSP support is disabled
security: No timestamping info available
security: Checking if certificate is in Deployment denied certificate store
security: Checking if certificate is in Deployment permanent certificate store
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
RTsSystem: Console output is redirected to internal log.
network: Cache entry not found [url: http://www.gapo.cz/chem/img/but0.gif, version: null]
network: Connecting http://www.gapo.cz/chem/img/but0.gif with proxy=DIRECT
network: Connecting http://www.gapo.cz/chem/img/but0.gif with cookie "GWeb!system=k9ESwMI; JSESSIONID=3E9E9FA335A44AC33D26CF1764EAB999"
network: Cache entry not found [url: http://82.100.20.62/svr/img/but0.gif, version: null]
network: Connecting http://82.100.20.62/svr/img/but0.gif with proxy=DIRECT
network: Cache entry not found [url: http://www.gapo.cz/chem/img/icons0.gif, version: null]
network: Connecting http://www.gapo.cz/chem/img/icons0.gif with proxy=DIRECT
network: Connecting http://www.gapo.cz/chem/img/icons0.gif with cookie "GWeb!system=k9ESwMI; JSESSIONID=3E9E9FA335A44AC33D26CF1764EAB999"
network: Cache entry not found [url: http://82.100.20.62/svr/img/icons0.gif, version: null]
network: Connecting http://82.100.20.62/svr/img/icons0.gif with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
network: Connecting http://82.100.20.62/svr with proxy=DIRECT
basic: Modality pushed

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
application must load and start classes
ACTUAL -
Appliaction fail to load.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.IllegalStateException: zip file closed
at java.util.zip.ZipFile.ensureOpen(Unknown Source)
at java.util.zip.ZipFile.getEntry(Unknown Source)
at java.util.jar.JarFile.getEntry(Unknown Source)
at com.sun.deploy.cache.CachedJarFile.getEntry(Unknown Source)
at java.util.jar.JarFile.getJarEntry(Unknown Source)
at sun.misc.URLClassPath$JarLoader.getResource(Unknown Source)
at sun.misc.URLClassPath.getResource(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at sun.applet.AppletClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at rts.system.RTsSystem.exitMessage(RTsSystem.java)
at rts.system.RTsSystem.exitMessage(RTsSystem.java)
at rts.system.RTsSystem.initInstance(RTsSystem.java)
at rts.system.RTsSystem.init(RTsSystem.java)
at rts.system.RTsSystem.initApplet(RTsSystem.java)
at rts.system.Main.run(Main.java)
at java.lang.Thread.run(Unknown Source)


REPRODUCIBILITY :
This bug can be reproduced often.