My internet stops loading pages after about an hour.

Hey there all, recently my internet has started to mess about. I have a Linksys router connected to the main desktop, 2 laptops, a 360 and a dell hand held.
The problem only occurs on the main desktop however. I use firefox and as soon as i try to load a page it says in the bottom left hand corner, where it usually says "done", "stopped"
If i have any downloads going at the time they continue and i can still use MSN etc.
I can't think why it would only affect the desktop and i have not downloaded anything recently that could have messed up. I run spyware doctor, spy sweep, ad aware and a McAffe virus scan each day and they never come up with anything.
My desktop has not been itself recently as well however, suffering from extremely slow start ups and shut downs - could this possibly connected?
On the desktop i have windows XP with service pack 2.
If anyone needs any more details i will try my best to give them to you.
I hope someone can help as this understandably frustrating.
Thanks

 

Uhhh mine does this too.. how come someone deleted my post..?

 

Anyone gonna help!!>>>!??!>!?>!?!>

 

Probably deleted as you need to make your own post describing your situation, but thats my guess.

 

My situation is the same as his.