Firefox/Flash problem

I'm having trouble with Firefox 3.0.7 (which I think has recently updated itself) and Flash 10; just since yesterday Flash items have stopped working well with mouse-over. I play a lot of Flash games, and many of them have, for example, text that pops up when you mouse over an item - this just doesn't work now unless I double-click. Another game which usually has a round cursor doesn't work at all (cursor vanishes and is replaced by normal arrow, which then has no game effect) unless I hold down the mouse button.

What is going wrong here? Where do I start to find out how to fix it? It's very frustrating - several games are unplayable.

Edit:Reinstalling Flash seems to have fixed it. Lucy 1 - Revision Fairy 0.