Just to jump in, can you "open" MSE and go to settings.
If the Real-time setting is ticked, your computer is being scanned all of the time it is turned on...
I will not ask, but it sounds like Windows 7 (7.1) installed.
Open MSE > Go to Settings > Real-time Protection > The box near the top should be ticked, and you are scanning all the time.
A Full or Quick scan (at request) is only a Deep file / folder scan, as your computer is already being scanned.
Most common problem = Are you sure that no other Antivirus is active (scanning) at all times ??
Please post a snapshot with Speccy for more system details -
See How to Publish a snapshot with Speccy <<-- Fully Read Directions Here (only Copy / Paste the link),
Do not accept any free offers with the program download as they are just advertising ..
Thank You -