I got this error after a reboot.
A restart of the Apache Tomcat service solved the problem though.
Error report:
Exception java.lang.OutOfMemoryError
Message Java heap space
Java version Sun Microsystems Inc. 1.5.0_06
Operating system Windows 2003 5.2
Tomcat home C:\Program Files\Apache Software Foundation\Tomcat 5.5
Stack trace java.lang.OutOfMemoryError: Java heap space