Investigating these "ghosts" further I downloaded a MIDI Monitor app for Mac OSX and now I am checking with it what's happening with my Polar. You really notice when Virus generates ghost notes but this app revealed that in fact my Polar does lot more than that: it sends foot controller messages (even when there's no pedal connected!), breath controller messages (?!), bender messages and occationally also note on messages. And all this without touching it! In my setup virus is connected with standard midi cables to iConnect midi which is connected to my mac. At the moment I left it over a night to record all messages and let's see what we got in the morning. Of course there's a little chance that iConnect is generating these messages but seriously I don't see this possible. It all points to Virus. To me it's very strange that it can send foot controller stuff without pedal connected.
I would really appreciate if those of you experiencing similar stuff could run MIDI Monitor (or any other app) tests with their units. Also, I wouldn't mind if someone with no issues would check his/her unit for comparison or for just in case. Remember that all those other things except ghost notes are much more difficult to notice. Without those ghost notes I would probably still be wondering why my Virus suddenly sounds different of behaves strangely.... Btw if you leave your Virus for longer period to record midi data with computer check that your computer won't go to sleep and shut off USBs cause this will stop the midi recording.
One more thing I will do asap is to check what's happening when Virus is in "local off" mode.
Anyway I really begin to feel frustrated with all these ghost issues. Maybe it's time to send my unit back to german...? I already contacted to Access support and let's see what they have to say. All this is really a hard for me cause Virus is a big part of my everyday musical work and almost all my live sounds need it. Being critical still I would not consider any other synth for replacing my Virus. Only thing I could think is to replace my polar with ti desktop + midi controller, if this is the only way to get rid of ghosts. Hopefully not.