Can Avast detect if spyware is installed on my computer

I read that programs like “Snapshot Spy” can be installed by simply sending an infected file to my computer or it can be directly installed with a USB if the spy has access to my PC.
Can Avast detect such a program?
Are there any programs that allow the spy to manipulate my computer?
I’ve had a few problems lately that point to a remote access causing havoc with my files.
Avast and MalwareBytes have not detected anything at all.

Many anti-virus programs can catch prolific spy software because they are often classified as “Trojan Horses”. Keep anti spy software up to date and make sure it is running in the background. This might not protect you against and from some of the spy software but it may let you know if any intentional spyware Trojan horses have been installed.
There are non-resident additional software solutions that you can use next/additionally to your avast resident av solution like MBAM and SAS to detect most of these malcreations.
MBAM and SAS are helpful but there is no such thing as 100% foolproof protection.
If in doubt ask our avast! forum qualified malware removers to have a look to see if you are spyware infected, go here http://forum.avast.com/index.php?topic=53253.0 and provide these experts with the demanded logs.
Their vast experience will guide you through the eventual removal routine!

Additional tip: best policy is to keep all your OS and third party software fully updated and patched (avast provides you with the software updater, use it!), pre-scan your links and downloads before you click away, especially when you venture out to places you haven’t been before! And again whenever in doubt, come here for some advice and assistance,

polonus

since SnapshotSpy seems to be a legit program, it may be detected as PUP … if you turn PUP detection on. pup detection is default off in all scan exept boot scan
PUP = not a virus / Possible Unwanted Program

Avast and MalwareBytes have not detected anything at all.
if you want somone to take a look inside, scroll down to OTL here http://forum.avast.com/index.php?topic=53253.0 follow instructions and [b]attach[/b] (not copy and paste) OTL diagnostic log