Help with Mozilla

I'm not sure I'm in the right place but if you  look at what I have to 
say you can then tell me if I am or if I'm not in the right place.
I had been using Mozilla for about a year or so.  I was very happy with 
it, much better than IE in my opinion.
About a week ago someone mentioned Firefox and Thunderbird.  I installed 
them both (Mozilla was still in my machine at that time).
Shortly after installation my computer began to momentarily freeze up. 
Then it began to crash (blue screen).  I thought I'd just switch back to 
Mozilla but when I tried, Mozilla wouldn't open up.  I uninstalled 
Mozilla then tried to open it up but still it wouldn't do it.  I 
uninstalled Firefox (I've kept Thunderbird but if problems continue I'll 
get rid of it and go back to Outlook) and then re-installed Mozilla, 
same problem, won't open up.  I found a support sight that suggested I 
delete the file, XUL.mfl.  I did and Mozilla opened up but then none of 
the bookmarks would work.
I'm now back to IE.  I've completely removed Mozilla and Firefox.  As 
I've said I still am using Thunderbird.  Though I've uninstalled these 
programs I'm still getting blue screen crashes and freezing (I was 
writing this post and had to reboot because my machine froze).
I never had these problems before these installations.  I would like to 
be able to use Mozilla again but I'm not sure what I can do to get it to 
  work properly.  My other, and probably biggest concern is the blue 
screen crashes and freeze ups (just froze for a moment but is now 
working again).
Does anyone have any suggestions?
Thanks,
Don............