Mike--It's been happening since a few days after I installed beta 2. I didn't post the problem on beta 2 because I was coming so late into that beta that I figured someone or several someones had already reported it. I didn't have time then to do a real search of the forums to be sure, so I erred on the side of stupidity.
It certainly is possible that this is due to third party programs, because I didn't install any games for the first few days.
I have 928K left. At first I suspected a memory leak from/by one of the four games (the only other apps I have installed). But I have booted up after a reset, started PlecoDict (essentially a clean boot), then pushed the home button and gotten a fatal error. If I get the error this way, there is no error message beyond fatal error and Reset. If I get the error after using PlecoDict for even a few minutes, I get MemoryMgr.c,Line:4475. Invalidchunk ptr. If I get the plain fatal error message, when I hit Reset, the Clie resets. However, if I get the fatal MemoryMgr error message, I can't get the onscreen Reset to work and I have to do a manual hardware Reset--i.e. stick the stylus' wire tip into the hole on the back.
As for what else I have installed (besides the programs that came out of the box with the Clie): solitaire mania, xoki, nono, hmaki and blackjack drop. Except for Solitaire Mania, these are old, old programs and could easily have memory leaks.
Let me know if you want me to uninstall the games and/or reinstall PlecoDict.
Sandra