And those 3 websites are?

The web sites were a bank, a cell phone company and a gaming company. I have dealt with them successfully for years using Firefox until three days age. I have been able to deal with them successfully over the past three days be using another browser.

please go through all the troubleshooting steps described at Websites look wrong or appear differently than they should (especially the part about js disabled or extensions interfering).

I too have this problem on many sites. Multiple refreshes sometimes cure it but I believe it to be a Firefox incompatibility with Java or Flash.

This page is extremely bad - http://www.bbc.co.uk/weather/2653261

Why has this problem only occurred in the past few days. Has there been an update in Firefox?

did you try the above steps? or reset firefox? Refresh Firefox - reset add-ons and settings

the problem has been solved by Reset Firefox

There has just been a new Java update - this did not help. I did another Reset Firefox - this didn't help either. Looks like I'll have to uninstall FF 18 until there is another update - and hope that works. I'm running XP if that helps anyone.

Just checked my GF's PC (also on XP) and she's got the same trouble with FF 17 - I'm out of ideas now.

I believe both FF 17 and 18 have just had updates - maybe this has caused it - it certainly hasn't cured it. I'll try a full uninstall, clean-up and reinstall tomorrow.

Reset Firefox worked for me on the Windows 7 PC. There has been no problem with Firefox on the windows 98SE PC.