Jason, thx for your swift answer.
I must make you dissapointed tough.
I've now tried the Mobile on three different computers, all with W7, and one with the old XpSP3 OS.
On all W7 machines (one HP, one Fujitsu and one HP laptop), the Mobile will stutter if the computer has been allowed to go down in "sleep" mode. This is regardless of the Mobile beeing connected or not to the computer at all times.
A reset of the Mobile does not help, but a restart of the computers do.
On the XP machine, it work ok even after letting the computer go down in sleep.
So, the solution is to shut all computers down befor using the mobile.
Br
Lasse