Severe Problem With HD and HD Recording-Please Help!

For some odd reason I can no longer save anything to my hard drive. Was working fine for months. Now I get an error message: (SEng) Device Command Aborted. Anybody else have this problem?I can still LOAD all the files that are on there I just cant save anything new. Can also still DELETE files. Only way I can save now is to the flash card
Also, I was simply trying to do a mixdown of a song. Had all sequences lined up correctly, went to add some audio tracks and I get message: (HD) Cannot Find Entry. Why?

Had to reformat hard drive (and throw away many good files) Hard drive is working okay again now but I still cannot get it show up on my MAC. I have formatted it on MAC (it showed up) but got error message on MPC. Format on MPC then its back to not being able to mount. Dammit! Starting to hate this thing. Shoulda kept my 2000xl, had no probs whatsoever (other than blowing zip drives lol) Spending way much more time just getting this to work than actually making beats ugggggh