How to fix: "I tunes could not be opened - unknown error (Ox666D743F)"
I just upgraded to iTunes 7. What could be more annoying than having it fail to start up with the error "I tunes could not be opened - unknown error (Ox666D743F)"? It turns out iTunes has a problem if you use 3rd party sound enhancement software or 3rd party sound recording software. You can temporarily work around this problem by disabling your 3rd party software. This can be done by going to:
Control Panel --> Sound and Audio Devices --> Audio
and selecting something other than your 3rd party software for the "Sound playback" and "Sound recording device" options. Or you could uninstall the 3rd party sound software completely.
UPDATE: iTunes 7.0.1 and 7.0.2 has some bug fixes, it seems to have fixed the problems with starting up when using third party audio utilities. So, try downloading the latest iTunes.