Firfefox help

For some reason on my other ( main pc) i cannot now get onto firefox. I have no idea whats happened but it was my default browser.
I have restored the pc to an earlier time and tried to reinstall FF 3.6.13 but nothing happens. All other browser work fine.
When i receive my emails i click the links which open my FF browser - now nothing happens.
I have even uninstalled FF and started again.
very strange!
anyone got any ideas on if i have locked it and how

I am now trying to download FF 5 direct from their site to see if that makes any difference


How very strange that seems to work! wonder now if i try and downgrade back to FF 3.6.13
well that seemed to work.

But how very strange how i had already uninstalled and tried to reinstall 3.6.13 but to no avail until i installed 5 then jsut downgraded. There msut have been something wrong as i have lost some of my addons!