FULL PRODUCT VERSION :
1.7.0_05 (which also installs 1.6.0_32)

ADDITIONAL OS VERSION INFORMATION :
Windows 7

A DESCRIPTION OF THE PROBLEM :
Sumac is a program that has been in production delivery via JWS for a few years. It works fine under Java 6 and Java 7. The installer stalls (crashes?) about 20% of the way through downloading if we put 1.6+ in the jnlp file.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
On a Windows 7 computer with 1.7.0_05), run this jnlp (which works fine if you remove the plus sign):

<?xml version="1.0" encoding="utf-8"?>
<!-- JNLP File for launching Sumac Application -->
<jnlp
  codebase="http://sumac.com/release32"
  href="http://sumac.com/release32/Sumac.jnlp">
  <information>
    <title>Sumac</title>
    <vendor>Softwood Technology Inc.</vendor>
    <description>Sumac Non-profit Software</description>
    <icon href="http://sumac.com/images/SumacIcon32.gif"/>
     <!--icon href="http://sumac.com/images/sumac_logo.gif" kind="splash"/-->
    <offline-allowed/>

<association mime-type="application-x/sumacSearchCriteria" extensions="ssc">
    <icon href="http://sumac.com/images/SumacDocIcon32.gif"/></association>

<association mime-type="application-x/sumacSQLImport" extensions="ssi">
    <icon href="http://sumac.com/images/SumacDocIcon32.gif"/></association>

<association mime-type="application-x/sumacReportLayout" extensions="srl">
     <icon href="http://sumac.com/images/SumacDocIcon32.gif"/></association>

    <shortcut online="true">
      <desktop/>
    </shortcut>
  </information>
  <security>
      <all-permissions/>
  </security>
  <update check="always" policy="prompt-update"/>
  <resources>
    <j2se version="1.6+" java-vm-args="-Xms96m -Xmx512m"/>
    <jar href="http://sumac.com/release32/Sumac.jar"/>
      <extension name="mail" href="http://sumac.com/release32/mail.jnlp"/>
      <extension name="mysql" href="http://sumac.com/release32/mysql.jnlp"/>
      <extension name="derby" href="http://sumac.com/release32/derby.jnlp"/>
      <extension name="CtCcommonsCodec" href="http://sumac.com/release32/CtCcommonsCodec.jnlp"/>
      <extension name="CtCcommonsLogging" href="http://sumac.com/release32/CtCcommonsLogging.jnlp"/>
      <extension name="CtChttpClient" href="http://sumac.com/release32/CtChttpClient.jnlp"/>
      <extension name="CtChttpCore" href="http://sumac.com/release32/CtChttpCore.jnlp"/>
  </resources>
  <application-desc/>
</jnlp>

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
It should install and run Sumac (which will put up a "which database do you want to use" window).
ACTUAL -
The download/verify/run window's progress bar goes about 20% of the way then stops, hanging indefinitely until it is cancelled.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
No error message happens.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
see the jnlp above
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
We have not been able to overcome this problem, which is preventing us from supporting Java 7 on Windows 7.