Firefox / Mac problem

I've started to have problems browsing the site using Firefox on my Mac. A lot, in fact most, pages don't load - I just get a blank page. The page tries to load content but then just stops and says 'done' with the screen still blank. This is Firefox 3.5.3 on Mac OSX 10.5.6. I don't have the same problem on any other websites.

I can use Safari on the Mac without any problems, and I can use Firefox on another computer (PC) without any problems so perhaps my computer is the culprit. Everything worked fine until about 2 days ago.

Not the end of the world, I know, as I can use Safari, but it is a bit of a pain having to continually switch between two browsers. If anyone has any thoughts on what the problem might be it would be appreciated - thank you.