I have a Windows 7 box (64-bit, Ultimate) that I had built last year. Attached to this machine is a Western Digital 1TB hard drive. Windows automatically mounts and unmounts several times an hour. The automount dialog box appears, which is how I know this is happening, and a "This drive must be formatted before it can be used" dialog box also appears. Canceling, both dialog boxes does nothing and the drive is fully readable and writable.
I have; downloaded and installed the latest drivers for Win7 from the mobo's web-site, formatted the external drive, tried different USB ports/cables.
Aside of the pesky dialog boxes, this issue is causing my backups to fail because the disk does not stay mounted long enough for the job to complete.