I was wondering, when I do a drive scan of Drive C, is the registry also scanned for the EFFECTS of virus activity (as opposed to virus creation signatures in infecting files)?
Also, are the effects of a virus running scanned for, instead of just the signatures of software that will create the virus in the first place?
Or do I have to run separate scans of some sort to scan for these, in which case, which ones?
The registry hives are scanned as files (strings) and not as a ‘set of registry keys’.
The registry activity is scanned by the avast resident.
The resident scanning, by default, will not scan archive files. The on-demand scanning will do it if you set so. I recommend a monthly scanning of avast with archive files turned on (at least on critical areas of the computer).
I guess what I mean is, say I turn On-Access Protection off.
Then I run a program which contains a virus or trojan, and it’s not detected because On-Access Protection is off.
The program modifies the registry, creates various files, etc.
Then I run a scan on the C drive.
Will Avast! catch those registry mods, etc. and see that the machine is now infected, even though it didn’t catch it when the infection occurred? i.e. it will catch the effects of the infection, not just the infection happening?
If it won’t, is there any way to scan for these infection results?
No. Only the infected files.
Not all the times, mostly not.
Yes, SuperAntispyware, SpywareTerminator, MBAM.
But, really, you’ll pay a very high price on disabling the antivirus protection. You’ll learn that it won’t worth…
Thanks much for your suggestions! Hopefully, nothing has yet been infected! 
you can also run an antispyware in prevent mode
here’s some free ones
Spyware terminator - without the Clam av and BHO toolbar
Windows Defender
Spybot T-timer
BO clean
Spyware doctor free from google pack
alongside Avast
Paid
SAS
MBAM
Counterspy
Spysweeper
I hope so…
Welcome to avast forums.
Feel free to come back any time you need help or just to change experiences 8)