Recover (D): Low Disk Space

This is just a suggestion, but have you tried running CHKDSK d: /F from a command prompt? If there is a problem with the file system - and it sounds like there is - this may correct the problem. You may have to reboot the machine for this command to work, but it is definitely wortha shot. This is a Windows system command so it is perfectly safe.

Why not get rid of drive d: altogether using vista disk management? Since there is nothing in that drive and you can't ever use it again for a factory image restore, recover the space and add it back to the C:

do you have your file system set to show hidden files and folders???

 

It could be restore points that are building up...

I used the option to delete all but the most recent restore point, that didn't solve the problem.  Re: the suggestion from someone about deleting the D:/ drive, I was denied permission to remove the copies of the Windows files that are stored there.  It's not encouraging to learn that Dell support was mystified, especially after watching my 3 month old $900 computer flat out die while searching for solutions on Vista's and then the Dell forums concerning this problem, and also a few other issues that arose after installing Verizon DSL service.  After owning 2 custom built computers, each of which served me well for 6-7yrs, I bought a Dell because of word-of-mouth.  But now people are telling me that Dell quality has gone downhill since they started outsourcing to India for tech support and whatever else. I wish the Indian people prosperity, but not at lowered standards for U.S. customers.