Re: No operating system
if you still have the western digital tools cd, try reloading the MBR (master boot record) program to the harddrive. if this works, save all your files to another drive and try reloading the OS. if system still acts funny, get a new drive.
i had one similar to what your describing but i have since made it a storage drive. so i cant say if this is a permanet fix or temporary. but it worked for me.
if you lost the cd you might be able to download from the western digital website.