It's on all of our machines after the 5300 engine update. I'm not quite sure what it does, but it's there, and as you stated, it's a fairly large file..
Hope this helps.
I'm seeing it too. The number seems to be random; on one of my systems it is wfv5, one is wfv24, one is wfv717, while on another it is wfv4A6. All are about 32 mb but I've caught one to be reporting 0kb after seeing it as 32 mb earlier. The file normally cannot be deleted because it is in use. It appears to be created upon bootup but it does not get created when you boot into Safe Mode. The number appears to stay constant to the machine (that is, it doesn't change when you reboot). I can't open the file so had our webmaster take a look at it. He confirmed that McAfee is mentioned in the file's header.
Check out these KB articles:
Doc ID: 616650
Doc ID: 616668
Thanks for the KB #s. I wish they went into a little more detail about how this actually works. Basically, it appears that 5300's better memory performance comes at a hard drive storage price. But considering the price of storage, that sounds like a fair trade-off to me.
Adding the new article numbers since the move to the InQuira Knowledbase located at http://mysupport.mcafee.com
KB53739 Reason why the WFV***.TMP is created by the 5300 Anti-Virus Scanning Engine
KB53756 Multiple *.TMP files generated in user TEMP folders after updating to the 5300 Engine
Knowledge Analyst (Global Online Services)