I'm not sure what to make of your problems... Language barrier, I guess. But about PulseAudio crashing, what exactly do you mean? I have myself seen notifications about how PulseAudio apparently 'stopped working', but music/sound was still playing perfectly. *Shrug* Maybe it fell back on pure, 'legacy', ALSA-only output.
Anyway, you shouldn't have to reboot - just logging out and back in should be enough. Or even manually restarting PA in your current session.
If Flash is lagging when it hasn't lagged before, try running without compositing (to "deactivate" Compiz: metacity --replace) and see if that helps.
Is your mouse a generic 2-button no-nonsense model, or some special fancy type, with plenty of extra buttons and functionality?