This application has failed to start because pthreadVC2.dll was not found. Re-installing the application may fix this problem
pthreadVC2.dll is an Apple Application Support dll, so in this case the 7 is most likely being caused by a damaged Apple Application Support. (iTunes requires a properly functioning AAS in order to work correctly.)
If you've got a 32-bit version of Vista, try the procedure I describe to Jroth in the following thread:
http://discussions.apple.com/thread.jspa?threadID=2256037
If you've got a 64-bit Vista, try the procedure I describe to fizzylove in the following thread:
http://discussions.apple.com/message.jspa?messageID=10918603#10918603
Note: since posting the fizzylove procedure, the download location for the 64-bit iTunes installer has changed. You can now find it at the following location (at the time that I write this reply, at least):
http://support.apple.com/kb/DL1037