Firefox behaving strangely

This is a problem which has been bothering me for the last couple of weeks. I use Firefox (and I hate IE7 with a passion, so dont go there...) for almost everything, but lately certain websites do not function normally.

Such websites include:
rogers.yahoo.com (text and images stretched exceptionally large)
google.com (the igoogle interface sometimes shows SQL errors, doesnt load the rss feeds)
youtube.com (works sometimes, other times tell me to install flash player 9, which I have)
aircanada.com (error messages (not every time though :s)
& the lost goes on

The odd thing is that all of the above mentioned websites function normally in IE7. I have tried with several attempts to fix this, but to no avail. This is what I have done:

Cleared all cache / cookies
Uninstalled, then re-installed firefox
Yelled at the computer, and cursed violently


Anybody else have this problem, or have a suggustion to make?

 

I think its something askew on my laptop rather then firefox in general. However, I am also constatnly ripping on Opera (which my friend uses), and I would be forever devastated if my friend saw me using Opera.

 

Ok, I fixed the problem.

I uninstalled firefox (again), and manually deleted all files left behind after the uninstallation. I got rid of files from "Program Files", and the files left behind in my user profile. I made sure I backed up my bookmarks, because doing this erases them.

After re-installion, All of the above websites worked normally.

 

**sigh**

The problem has surfaced again. This is hopeless...........