External HD trouble???

Hi all. I have an odd problem. I have been using a 1tb external WD elements hd for my time machine back-up and as an external hard drive. I formatted half the drive to use as time machine, and the other half is formatted as an external drive for use on both my macbook and my wife's windows machine. For months this setup has been working just fine. Recently for some odd reason my macbook stopped recognizing the drive. My wife's windows machine easily recognizes and is able to read the side of the drive formatted for external drive use. My macbook refuses to recognize both the external drive half of the drive, and the time machine half. I am using the same usb wires for both machines, so the wire is good. I am using the same usb port on my macbook for other stuff in addition to the drive, so the port is good. When I plug the drive into my macbook, the little blue light on the back of the drive lights up and I can hear the drive spinning up.

When I run disk utility, first aid, it starts then says first aid stopped repairing disk, first aid was unable to repair disk.
First aid will recognize the drive, but won;t recognize the two partitions on the drive, I even tried formatting the drive using utility, with no luck.

When I try erasing the disk using disk utility, it gets caught up in the unmounting disk phase and eventually is unable to erase the disk.

Any suggestions?

p.s. If it matters, I am running an aluminum macbook, OSX 10.6.2, and have all the current updates.

Try using Disk Manager to format the drive from your wife's computer to see if it will format at all. Unfortunately with a drive that large, Disk Manager will only format it to NTFS.

Or you could download and use GParted (Linux utility) to format the drive to FAT-32. Note: You must first burn the GParted image ISO file to a CD. Use Disk Utility.

Run the GParted CD from your wife's computer NOT the MacBook.

Regards.

Thanks chscag. Unfortunately my wifes computer will only recognize the part of the drive partitioned as an external drive, it will not recognize the time machine partition. My macbook will recognize the drive when i plug it into the usb port, in disk utility, the drive shows up, the partitions are listed under the drive name, but the partitions are not accessible, and none of the disk utility options will work at all.