I had problems with this on 2 client machines that I was using to
import. I was getting something along not enough space on the drive. I
finally found that my temp  dive was redirected to documents  and settings
and yes I had too many. I deleted these out and was back on track.

I have not really decided what to do to be proactive. I just happen to
be looking at Q275517. Might be of some interest to you also. I think
a log on/off script could be used to clean up the temp area.
Interesting that Disk Cleanup does not clean a redirected temp. I would
have thought it would.