Yesterday I had to phone Logitech's support as my new mouse,the MX518 was not recognized by Windows at all, I have windows 7 64 bit.They were unable to help, in fact I was told to get in touch with Microsoft as it was a problem with just my version of Windows 7,64 Bit. The mouse worked fine on the XP machine I tried and was assured that it should definitely worked with 64 Bit.
I eventually went into the bios and changed a setting in the USB category to auto and when my PC booted my mouse was seen and driver installed and it now works.
I change the Legacy USB Support to auto.
Worth a try, perhaps.