Freeze Up

[#1]

I have Windows 7 and I have noticed the last few weeks that sometimes I am unable to close a window when I click on the x top right my computer freezes up and I have to get the Start Task Manager to clear the running website,is it possible that I should close each website when I have finished with it

[#2]

Which browser

[#3]

My browser is Firefox

[#4]

Have you just updated to Firefox 6

[#5]

No I have not upgraded will this help my problem

[#6]

It might have caused it which was why I asked
Does it happen on all sites or only ones which use Flash
If it is on every site - try this http://support.mozilla.com/en-US/questions/826509