Its funny that we are discussing this and just last night through IM I had a friend ask me why her Copy/Past stopped working in Photoshop... so I had her shut down photoshop and re-load it to solve the problem.   If large amounts of data is stored in the clip board, photoshop will ask you if you want to purge the data before shutting down and that will do the trick.

Af for FireFox... its is a great browser and I love using it, however it does have memory leaks and the odd crash here and there.

I've found that if you open websites in a single window but Multiple Tabs using the CTRL-T  key combination, it has a less of a chance from crashing.