Explorer (not responding)

Hi, I need your advice. Over the past couple of days, I
have noticed that my computer is not responding (and
basically freezes up), after it is used for a few minutes
to access the internet or to work on a Microsoft Office
product. Here is a good example.. I will go into the
Internet (using IE 6) and then a few minutes later I will
exit IE 6 and get back to my deskyop. At that point, I'll
click on an Icon or the system tray and the hour glass
just comes and the system freezes up. I hit Ctl-Alt-Del
and the menu says that Explorer (not Responding). I hit it
again and I get te dreaded blue screen telling me that the
system is busy and that I can wait or hit Ctrl-Alt-Del
agaiun to restart. I restart and everything is fine again
for a few minutes and the the same error repeats. I use
Windows ME. I also ran Ad-Arae to scan my system for
Parasites and ran a Virus Scan and everything appears to
be cleaned. Any guidance that you can offer would be most
appreciated. Thanks.