Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
Good day Timmy
As highlighted in the product documentation, this is a known bug (and it is not dependant on the installation - as long as you have the green copyright message everything should be good to go).
It is due to a contact point/balance instability - all the solutions I have tried ended up being detrimental to flight behavior... hance, since the issue disappears when the aicraft is in motion, I preferred not to touch the static ground dynamics as everything else seemed good.
Note that this unfortunately applies to both the freeware (version 2.XX) and the payware versions (version 3.XX).
Sorry for that - I hope it does not spoil the fun too much.
Dino