iTunes 11.0.4 on XP new install not responding, CPU 100%

Just downloaded and installed iTunes 11.0.4 on Windows XP SP3, launching it from the install dialog final step. Opened the File menu. iTunes.exe went to 100% CPU and is not responding. The File menu is still on the screen, getting in the way. Runs at 100% for hours. The iTunes library is empty - no chance to add a single song to it. What can it be up to? I ran earlier versions of iTunes with little problem - what gives? How can I determine what it is attempting to do as it apparently loops its way to nowhere?

Thanks for your help

Cheers