Java SE (Java Platform, Standard Edition)

I've been working with Java on the Mac platform for quite a while now, but we've been noticing a Windows XP problem at work that is over my head:

"A javaw.exe process is launched each time I start the app. Quitting the program does not kill the javaw.exe process. After starting and quitting the app a number of times, my system's performace really starts to degrade. I have to manually kill all of the javaw.exe processes to liberate my RAM. "

Normally we open it just by double-clicking the jar file (since it has a manifest in it), but we've also resorted to using the console the open it. Nothing seems to make a difference.

I'm positive that System.exit(0) is being called after I save everything and close all my windows (I added console output to verify that).

Am I misusing System.exit()? Does anyone have any experience with this problem, or knowledge of the subject?