Sorry for the delay. Had to scan multiple times, each one taking, when fully completed, probably ~11 hours.
I scanned once, and at the end of the scan there was an error message saying that HouseCall had asked C++ Runtime to terminate in an unusual manner. Then I got an error message from HouseCall, and it closed without letting me deal with the threats it found. Without detailing all the times I scanned and everything, I ended up stopping the scan part way through on two occasions, and removing the threats that way. I finished scanning it just a bit ago, and it found no threats this time, but still had the same error trouble as the first time.
If you want the error info, I copied down most of it.
The threats found had the following names:
-Eicar test file
-Hidden file (it said this was a rootkit, though apparently it was downloaded as part of a webpage, and was undeletable in the past)
-HKTL Bypass (it said this was spyware)
Regarding dllhost.exe, when I terminate it, it instantly starts up again. I use a program from Portable Apps called Process Hacker, and in the description it says "COM Surrogate." Don't know if it matters, but I noticed that its priority is set to "below normal" in task manager. Also, a few days ago, after I had suspended the process, I noticed the sound was gone and upon looking I found two dllhost.exe's. I suspended the second one as well, and no further ones started up.
Edit: After the scans were all done, dllhost.exe was not there. So I restarted, logged into the regular account I use, and played some Halo online. In about 5 minutes dllhost was back.