Something Caused Some Apps Not to Open Anymore..


After playing around with the last stable beta-release of VLC-player (0.8.4) on a G5 dual 1,8 under Tiger 10.4.1, I have problems opening iTunes, Jam, Cocktail and some other apps: some open, but won't display their windows.

I'm quite experienced, did all the regular troubleshooting, deleting prefs and such, but I cannot put my finger on the problem... Rebuilding the databases, fix permissions... nothing seems to change the behaviour of the apps (not even under root) that were working properly just hours before: they still run fine from my backup-system

It can very well be it's related to some other install or action I did, but I'm sure something has changed system-wide, but all I can make up from the console are these returning errors:

"AESendMessage returned error -1712"
"CGXOrderWindow: Operation on a window 0x6 not owned by caller..."
"kCGErrorIllegalArgument: CGXGetWindowProperty: Invalid window"
and many more windowserver-related errors.

I'm afraid some framework or coreservice has been up,-or downgraded, but I cannot put my finger on it... been staring at this for two days now: do I have to re-install or is there a fix that might work?!

Thanks a zillion for nay advice or help: I'm quite desperate.