Strange DAT files

For the past 6 months, I've noticed that some strange .dat files started to show up in the Task Manger. They all have a random name of four letters ending with .dat. For example nkek.dat.

I used to run NOD32 as on-access scanner before, with every security settings maxed out. NOD32 never gave me any warnings on these files, but I manually closed them, since they were suspicious.

These nasties still pop up to date, and these days I'm running DrWeb as on-access scanner. DrWeb always catches them and they have names like Trojan.DownLoader.1864. I think they reside in Temporary Internet Files.

I have scanned my computer with DrWeb, Kaspersky, Ad-Aware and Spy Sweeper and my system seems clean.

Also, I've scanned several of these .dat's at Jotti and VirusTotal, and DrWeb is the only one who recognize them as malware.

Does anyone have any info on this kind of malware?

Thx.

Jotti -> http://www.imagehosting.us/imagehosting/showimg.jpg/?id=304898

VirusTotal -> http://www.imagehosting.us/imagehosting/showimg.jpg/?id=304908