Ignorance and callousness are not virtues
I think it's likely an extension conflict. Also, (you're on a windows machine?) check for any browser-based anti-malware scanners/blockers and disable them if you find them (like zone alarm?).
Go into incognito mode and disable everrything but the bare minimum you need (java, greasemonkey, divx webplayer, windows media player plugin [I'm not sure about this, but think it may be necessary to process the .avi container] - I think that's all...) See if it works.
If it does, re-enable stuff one at a time and test.
A bleeding heart is a symbol of holiness, a symbol of compassion, not an epithet
When our discourse sinks to the level of meaningless, pejorative labels and personal name-calling rather than honest reflection and reasoned dialogue, we are no longer a people, but a mob