lyno90,
Let's see if we can get your iTunes running in your main user.
1. What version of iTunes / Quicktime are you running? You should have iTunes 6.0.4 and Quicktime 7.0.4. You can get the Quicktime version from the Quicktime control panel. Start menu -> Settings -> Control Panel -> Quicktime. Click the "Register" tab. Click the button that says "About Quicktime". What number does it have at the top of that window for the version of Quicktime?
2. Make sure you don't have the compatibility mode accidently set. See
this knowledge base article for instructions.
3. If you've got iTunes 6.0.4 and Quicktime 7.0.4 and you're having this problem, we should collect a crash log and send it to Apple so that the engineers can look at it.
Typically, you'll need to configure Dr. Watson on your PC in order to generate crash logs. Windows start menu -> Run. Type in "cmd". Hit return. At the prompt in the command line window that comes up, type in
drwtsn32 -i
And hit return.
This will create crash logs in Documents And Settings\All Users\Application Data\Microsoft\Dr Watson\. There'll usually be a file in here called "drwtsn32.log" If there's already a file there, it most likely has multiple crash logs in it (new crash logs are just appended to the end of the file). So, delete this file. This will make sure you're not sending extra information to Apple that they don't need.
So, get the machine setup to collect crash logs, do the thing that makes iTunes crash.
Send it to the apple moderator as well as information about what version of iTunes you're using. Tell her Toonz sent you. It doesn't hurt to put the URL to this discussion thread, so that whoever gets it has some context.