Help-8100..memory errors

I bought my 8100 (512mb RAM) last year. As I added more programs to it (not many!), I started getting frozen screens. I could not ctrl/alt/del nor do a hard shutdown. I could ONLY shut it off at the power cord ! When I turned it back on, I would get "The amount of system memory has changed. Press F1 to continue." At this point the scandisk would run. This has been going on for months now and I am finally starting to do something about it. Someone suggested it was the Windows ME that came with it. Others suggested bad RAM. Any suggestions? I am calling support tomorrow a.m.

Thanks!