External USB HD switching to read-only

[Outlaweyes]

I have a Western Digital 500 GB "My Book" external drive (USB connection) hooked up to my Hewlett-Packard Pavilion Elite PC. In the last few days, I have been having an odd problem with this HD. It spontaneously decides that it is "mounted for read-only", and I can't write to it or create new directories. If I restart my computer, the problem goes away ... for a while. Anyone know what might be causing this problem?

[labtech]

High chance the drive may be failing. Check SMART attributes and read on those that seem to have problems.