Do you have a HP PC? If so you need to goto hp.com and look up updates for your model, some of there models have issues with iTunes after doing a restore and they offer a patch for models that are affested.
Try uninstalling iTunes AND quicktime from the control panel in windows, disable antivirus then goto apple.com and download/install the latest iTunes.
If that doesn't work try installing the stand alone version of quicktime here
http://www.apple.com/quicktime/download/standalone.html