dll.host.exe virus??

I have a strange one (aren't they all?). My HP laptop (Vista Home Premium), is super sluggish. Ran MBAM, SAS, Norton, CCleaner. Found a bunch of stuff....PuP's, Trojans (including "backdoor.mevade), etc. Got rid of them, but still sluggish. I noticed in task manager, that I have 28 instances of a process called dll.host.exe, and they're chewing up a ton of memory. I tried running RogueKiller, but it hangs up about 40% thru the registery scan, so I had to stop in. BTW, I'm doing all scans in safe mode. I know there's a legit file by that name, but I never saw a dll show up on the processes tab before.
Any advice/info would be muchly appreciated!!
dondd

 

Thanks Kestrel13 for your prompt response. I'm currently in hour 6 of a MS Securities Essentials scan I'm doing on the hard drive I connected via my SATA adapter to my other PC. It's taking a long time, but as it's connected thru my USB port, I suppose that's normal. Tomorrow, I should have some results.
dondd

 

Kestrel13, OK...I think I finally got it. What I believe did the trick, was that I pulled the HDD out of the laptop, and with a SATA adapter, scanned it using Security Essentials on my desktop. That scan ran for 10 hours, but it found a bunch of Trojans and a few other things. After cleaning that up and reinstalling the HDD, I still had the dll processes, but RougeKiller was now able to run without a hitch. It came up with a bunch of stuff as well, and when I restarted the laptop, the dll stuff was gone. So then I re-ran some scans with MBAM, SAS, and ASC....came up clean, and the laptop seems to be working normally. I'm now going thru a slew of Windows updates.
Thanks for the interest in my problem!!