Try running Firefox in Diagnose Firefox issues using Troubleshoot Mode. If it functions properly in that configuration, then one of your add-ons is the culprit.

Tried, didn't seem to be the case. The other thing that might be happening is my virtual memory thing.

You can check the Virtual Memory settings here: Control Panel > System > Advanced > Performance > Settings (Advanced tab)
Windows can manage more memory then is physical available and that memory is stored in a page file on your hard drive.
If the size of that file is not large enough and all available memory is in use then you get the Virtual Memory is low warning.
Make sure that you have at least 1 GB or the recommended setting for the Virtual Memory.
If you have less than 1 GB physical memory installed on your computer then if possible add more memory.

• http://support.microsoft.com/kb/555223 - RAM, Virtual Memory, Pagefile and all that stuff
• http://en.wikipedia.org/wiki/Virtual_memory

Yeah, before i had the virtual memory set to "no paging file" and now i setted it to custom set of min. 2 mb and max 4.5k mb. My ram is 3 gig so i guess this setting is okay.

Use at least the recommended setting for VM. Windows XP isn't managing memory very good, so you need to have enough VM set to avoid problems. Firefox 4 may need more memory than previous versions.