Thanx for your tips!
But well, since yesterday it works well again. This problem just occured the whole Thursday, but only at work (later on in the evening at home everything was fine) - and I still can't imagine why...
@Pilchard:
Unfortunately I was alone at work on Thursday, so I couldn't let somebody else test it for me...
@wolfy:
Well, it wasn't that I upgraded my browsers or installed a new plug-in or whatever. Everything was the same like for instance on Wednesday, too. I can't believe that it was a problem of a version or incompatibility then... and I'm using Adblock Plus as well - had no problems at all.
Maybe it had something to do with the proxy server at work as it is sometimes unstable...
But whatever, now it works again and I can slash some more gods ^^
Let's hope that's it then ;]