Iphone not recognized by PC

Since updating to iTunes 7.1.1 my 2G iPhone (original) is not even recognized by my PC. When I connect it to the same USB port that I have used many times before to sync the iPhone, all I get is the "Device failed to connect" sound. There is no sign of the iPhone (or any unidentified USB connection) in My Computer.

I have purged my PC of all previous versions of iTunes and any other Apple software and have re-installed all of the necessary software to no avail.

I use Windows Vista Ultimate on a 1.66 gHz x 4 gByte Ram PC.

Help
jpgeorge6000