Thanx for answering
Well, I tried everything sugested on this forum withot any result.

Then, I tried to reset all my Firefox preferences and profile.
I tried to see if Firefox was still "working" afterthat, : it did.

I tried again to immunize : no more improvement, still the same problems.
I lauched SpybotS&D for browsing everything. At the end of browsing, when I wanted to "fix all problems", a Microsoft window told that it had to close the Spybot program for security (before corrections were done).

Afterthat, Firefox didn't work!!!

After hours trying to fix the problem (in windows data(?)/données in French protection, setting Spybot S&D in "exceptions"), Everything was blocked.
(Difficult for me to explain and translate what I did in English, like "système de prévention des données Microsoft" for instance...)

I had to reset/restart computer and retore system as it was yesterday.

Is it because I'm using Firefox 2.0.0.16???
I still don't want to go to Firefox 3, because when I tried, I lost all my favorites.

People from French Firefox forum Geckozone cannot answer my questions either.

I'm kind of desperate.
Ad-Aware is too heavy and runs too slowly...
Perhaps I should try AVG full security version, but it's expensive and seems not to be compatible with other security systems...
It's such a mess..

What do you think about these experiences?
Should i have 2 Anti-spyware, 3 firewalls and 3 antivirus to be peaceful and quiet again????