The command that fails is
C:\jdk1.5.0\bin\javac -source 1.4 -classpath C:\jdk1.5.0\lib\tools.jar -g -d ..\generated\saclasses <long list of .java file>

The failure occurs when the above compile is done in directory:
      c:/build1234512345678901234567890123456789012345678901234567890/hotspot/windows_i486_compiler2/generated/

The error message is

Z:\xx\tiger-control\hotspot\agent\src\share\classes\sun\jvm\hotspot\debugger\win32\coff\COFFFileParser.java:1202: error while writing <anonymous sun.jvm.hotspot.debugger.win32.coff.COFFFileParser$COFFFileImpl$COFFHeaderImpl$DebugVC50Impl$DebugVC50SrcModLineNumberMapImpl$1>: ..\generated\saclasses\sun\jvm\hotspot\debugger\win32\coff\COFFFileParser$COFFFileImpl$COFFHeaderImpl$DebugVC50Impl$DebugVC50SrcModLineNumberMapImpl$1.class (The system cannot find the path specified)
                public Object computeValue() {

If I shorten that long c:/build..... pathname by 4 chars (or so), then this error does not occur.