Cannot fix Quicktime/Youtube/flash problem

Okay, here's the sitch- i am running an older (powerpc) macmini (10.4.11) with all the most recent updates (safari 3, QT 7.3) etc. Anyway, I always get the Q? symbol on youtube, and any other site that has Flash media (myspace, etc.). I have looked all over the internet the past few weeks and have tried every fix i have come across, but so far nothing has worked- for a while, i could just quit safari and re-open it and after a few tries, the problem would not be there, but that is of course not a permanent fix. I have uninstalled and reinstalled all extra QT stuff (flip4mac, perian, etc.), have disabled flash playback, put MIME settings back to default, taken the quicktime.webplugin (whatever they were) plugins out of the internet plug-ins folder, etc., downloaded newest version of flash player and nothing is working. This is getting quite irritating (especially since it's finals week and i gotta have some anti-study internet time to let my brain rest). Any help would be greatly appreciated.