The Maxtor diagnostic utility is PowerMax. Instructions are available on this webpage. Once you've established if there are any defects, post back.

If there are any defects, the next most important step is to mark any bad sectors in the file system and attempt to recover any damaged files. Do this by running the command prompt (Click Start, Run and type cmd) and use the the following command: chkdsk c: /r

You will be informed that the drive cannot be locked and asked if you wish to do this next startup. Choose yes, then reboot the system. This will take a while, possibly up to an hour depending on the state of the disk, but it's very important step to try and prevent data degradation and preparation to ensure any necessary backup attempts will be without error.