Internet browser(s) crashing problem.

I have been searching for a solution to this problem for sometime but with no luck.
I am on a Toshiba Satellite Laptop using Vista Home Premium.
My internet every now and then crashes but my MSN Messenger will work.
I have tried I.E, Firefox, Opera and am currently using Google Chrome but no matter what browser I use the problem still happens.
Whilst searching for a solution I found it could be Flash causing the problem so uninstalled and reinstalled but that didn't fix it.
I have found it happens when I visit a site where there are video's or several pictures ( e.g. auction sites ).
Hope someone can help =)

EDIT: Forgot to mention, the only way to get my internet working again is to to reboot my lappy.