Why does my QuickTime installation keep breaking after about a month?

[ravenvii]

My QuickTime installation keeps breaking after about a month. When I first installed it, it works fine in Safari. But then after a while, it suddenly couldn't play anything. Just keeps saying it doesn't have the software to play the movie, and the software couldn't be found on Apple's servers. WTF?

Repairing permissions doesn't help - the only way to fix this is to download QT again and reinstall it. Then it works fine for the next month or so.

[ravenvii]

Well it went and did it again.

I reinstalled QT last week, and it works perfectly... until today when I tried to view a trailer... got the broken QT icon again. ARRGH. If I try to play movies directly in QT (with a file) it works. But in Safari it doesn't. Yet, if I reinstall Safari, it still won't work. It's "fixed" only by reinstalling QT. What's up with that?

Can anyone help???