I also checked with another computer, even two different computers on XP and Vista, but result was same. Both of other computers have never seen any other Garmin device or programs.
The conclusion is that it is something internal in device FW or elsewhere.
So far my decision is to return it to Garmin as device is under warranty.
I have all copies needed for device /full backup, region 41, maps/ and I have enough experience to weep properly unit and to restore it in full.
But my understanding is that: why should I /user/ bother myself with all that stuff? Imagine that I do not know what to do or by chance I do something wrong or things went wrong for whatever reason? If Garmin Co is so advanced, well known and they proclaim that they are at least the best , then lets prove it. In the end of the day my money are with biggest value for me. And as the unit is not cheap at all, why should I bear any risk instead of them?
Unit goes to Garmin today. I'll keep you posted about results.