If you are getting blank emails (no subject, no body, no attachments, no To). All you see is a From address for whom you usually don't recognize (but it could be someone you recognize). This is 99% that someone else has a virus called Backdoor-IW A.K.A. 3dstars, I-Worm.3dstars, w32.3dstars.worm.
Mcafee seems to have the most info about this worm, followed by Kasperov and some others. Symantec has little info that I could find. While you are not infected, someone else is. The virus has a bug in its code that spits out the blank email. Its obvious that some people are infected, but its hard to see how this bug is actually spreading since it has a bug that doesn't send out the viral attachment its supposed to, to infect others (see my point?); so if it doesn't send out the virus because of a bug, how are others getting infected unless there are some versions that don't have the bug!?
Hope this helps.

Perhaps you should post this in the Security/Virus forum.