Remove Microsoft .Net Framework Assistant From Firefox
Have you noticed one of these problems:
1. popup saying that NET Framework cause stability problems
2. strange firefox crashes
3. yahoo mail (the classic version) doesn't respond correctly when you choose things and send messages (that "loading" message an slow response or nothing)
4. some times just can't load new URLs.
Take a look at the installed add-ons in Firefox search for an add-on called Microsoft .net Framework Assistant.
That add-on is different from most other installed add-ons. The first thing that you will notice is that you cannot uninstall it as the uninstall option is inactive in Firefox, specially for versions "0.0.0" or "1.0.0".
First try to disable it if it's active. Start Firefox again and check.
You might also realize that you did not install that add-on actively which means it must have been installed by another application.
If you use Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:126.96.36.199) Gecko/20090729 Firefox/3.5.2 , you can go to this page: https://addons.mozilla.org/en-US/firefox/addon/9449
and upgrade the .Net Framework Assistant, and then you can uninstall the extensions or just keep it "disabled".
If you uninstall and after restart it still is there try this: http://support.microsoft.com/kb/963707
The pop up from Microsoft's framework error message or the "Just in Time Debugging" from Microsoft is annoying but a very easy fix.
Go to the control panel under the Start Button. Click on Internet Options Turn off the Microsoft Debuggers and your Firefox will never have any more issues.