deserter85,

I don't think it got fried because you left it on 24/7... I think the hard drive has a problem that indicates it may be ready to fail. Stop writing to it and get a new one.

If there are any files on the external that you want back on your Mac, put them back there now while it is still able to do that, before you get a new one.

I only use my backup hard drives every day or two to update my backups, but leaving one on all the time shouldn't be a problem.

Noel