My windows 98 SE is regularly freezing up on me.  Every
time it seems to happen I seem to be accessing an email in
OUTLOOK.
I usually have multiple programs running at the same
time.  Could this be happening due to lack of memory?  I
have 128MB of ram.
When it freezes up, I can still work in some of the
windows I have open, but Outlook and any emails or
reminders that were open are not accessable.  I can't
click on the toolbar at the bottom of the screen.
Anything 'outlook' doesn't show up when doing a Alt+Tab or
looking at task manager. As soon as I minimize any windows
that were accessable, they become unavailable.  
What is causing this?  Please help.
Jason