I seen that msg quite a few times with 3rd party anti virus. at least for "Spyware and unwanted software protection (important)" msg.
I think this happens with all anti virus that are 3rd party it did with me anyways while having Avast.
Trust This PC msg I never got this. Is this machine authorize as trusted?
I also have a hub for 6 extra usb port AC powered.
Microsoft LifeCam 720P
HP LaserJet Pro M1212NF
2 x 8 Port GB Switches
1 X Netgear Router Netgear WNDR3700 v2 W/ DD-WRT
and Much more
Sometimes the warning happens because the anti-virus has not yet fully started, so you see it for a second then everything is good. I wouldn't worry about it unless you see other evidence of a malware problem.
If you have a password to logon to your system wait a few minutes after booting before typing the password to log in. Then your pc can finish booting all the important systemfiles, as well as the virusscanner.
You also might want to try a full scan for virusses.