Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

Thank you for your reply. I have just tried both of these things and it hasn't made any difference unfortunately.

Didn't work for me eiher...what a pain.

This is probably an issue with the new Yahoo code that Yahoo needs to fix on their site.
You can try to contact them or post on a Yahoo forum if there is such a forum for problems with Yahoo! Mail.

I did all the above and that did not work.

I browsed in save mode for a week, no problems in yahoo mail.

Then I disabled all plugins and extensions in normal mode, still good.

Then I enabled one by one , testing a few days at the time. I finally got it narrowed donw to ONE plugin: Firebug.

I really need firebug. I tried Opera (got the debug-tool integrated in the core), but that does not work half as nice as Firebug.

I tried to post on the firebug forum, but it seems they have no forum at all, only that inaccessable spamalot groups-thing.

Please someone debug Firebug.

I had the same problem and so I disabled the Yahoo tool bar and everything is fine now

That isn't going to work for me because I don't have the Yahoo tool bar in my browser! Thanks anyway.