Urgent for itunes users

Deleted everything, ran registry cleaners, installed itunes. Finished installing itunes and opened it and!

"Itunes was not installed correctly. Please reinstall itunes.
Error 7 (Windows error 126)"

hit ok and then this popped up again

"The program cant start because dbghelp.dll is missing from your computer. Try reinstalling the program to fix this."

Problem being is ITUNES is whats causing this and not letting me run other programs either...