How to perform full scan?
I right clicked the icon and checked full scan, but it just says "1 on demand task" and it's not actually scanning....

The free version waits, till you are no doing anything on the computer to run the scan.
It has a very thin wrap-around progress bar...hard to see.

Not sure what you mean, as people are always doing stuff on computer
for instance: I have web browser open, runescape client open, IRC chat open, skype open, etc