I've had the displeasure of experiencing a Tomcat JVM core dump on me not too long ago (in a multi-user development environment, fortunately) on a Sparc/Solaris box. It turned out to be due to insufficient swap memory in the system. I didn't see any OutOfMemoryExceptions raised prior to the crash, so it wasn't that obvious, but the top command came to the rescue in the end.
Good one ;) It reminds of another time, where I had internal crashes occurring due to a low limit of file descriptors (ulimit -a will show you the limits). That one was frustrating ;) I'm sure many people on this list of horror stories with seemingly random crashes...
I've experienced even more random crashes (SEGV). It turned out to be bad memory (or bus), and it only showed up under pretty heavy load. :(
-chris
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