Right, thanks a lot, I've finally managed to solve it somehow, at least for the time being And yeah, I get CPU problems rather frequently, my current one runs at 1.6 GHz, so it's not a surprise...
Saw your playback problem question while reading Vexx's profile... while I'm hesitant to mention it because it's a pay product, CoreAVC has been known to dramatically improve playback performance on slower machines over CCCP's built in H.264 decoder. Also, be careful with multitasking, I've found some flash heavy websites can burn through a lot of my CPU if I have them up in the background.