To summarize what was previously reported; it was observed that there were cases when Windows would lock up for brief periods of time. These lock-ups seemed to coincide with long GC runs so from there it was surmised that GC running in the JVM was causing all execution threads running in Windows to block. The effect was most noticeable when Eclipse had been running for long periods of time. The update on this tread is that by using Ptrace it was discovered that the JVM is running threads at priority 15. To understand exactly what this means one need to understand that most application threads run at a priority of 8 and one must have admin privileges to run above 10. Anything above 15 is considered to be a real time thread. So when all is said and done, threads in the JVM did have the capability to block Windows threads. Good news is that it will be fixed in the JDK 1.5.0_06. Until then you can use the following flags; -XX:JavaPriority10_To_OSPriority=10 -XX:JavaPriority9_To_OSPriority=9.

Also see http://192.18.37.44/forums/index.php?topic=10269.0.