I searched and found a related error that mentioned QuickTime being the issue, but I haven't done any updates to QT or Windows and AE was working fine last week. Out of the blue this morning, I get this on startup:
After Effects warning: A problem occurred when processing OpenGL commands.
I am running After Effects CS3 on WinXP SP2.
Any ideas? Some setting I accidentally turned on/off, maybe?
Your graphics card configuration changed - intentionally or not, something is different than before. Did you change the resolution? Did you unplug and replug a monitor? Played a game on the same machine? Installed an alternative MediaPlayer or updated Windows? All things to consider. To be on the safe side, also trash the prefs.