There is a admin tool called "Event Viewer".
It is under Start->All Programs->Administrative Tools->Event Viewer.
If you run that, you can look at the system errors reported in the background.
It might tell you why MA3 has the ! mark.
Note that just because you happened to use 3 virus checkers and returned no Malware does not mean there isn't.
If you are not noticing any other slow down from any other applications, then it might be safe to say there is no Malware.
I use MalwareBytes and AntiSuperSpyware myself. Rootkits however sometimes can't be found by just a normal Spyware application.
I had to use a tool called ComboFix to clean a couple of computers that were really infested. The computers were not mine.