iTunes doesn´t work anymore

iTunes worked very fine some time ago.
Until the day I erased some temporary files on my drive.
After this I can´t start iTunes anymore. For each use of it I have to uninstall and to reinstall the program. Then it works for one time. Then the problem returns.

The support of "nice" apple was not willing to help me.
Does anyone of you know the problem and has a solution?

Greets Markus