[RTTY] K3+MK2+N1MM problem

[Fabi va2up]

Hi all,
I"ll take my chances here and ask...
Many changes to station lately and using in radio 2 position a K3 with Micro Keyer 2 interface all driven by N1MM software with MMTTY engine. As a startup point I love all 3 or 4 of them and although a fairly new K3 and MK2 owner/user, I can tell quality when I see it!
Since the changes I am faced with a problem. Here's what happens:
 
1) either a ptt freeze in the middle of TX routing that will require shut down of the K3 in order to resume operation (while radio 1 and MMTTY engine are still behaving normally, that is a 756 pro2 with Rigblaster Plus interface)
 
or
 
2) ptt freeze and computer shutdown and reboot showing blue screen warning.
 
This happens in both LP or HP. I have tried to cover all possible rfi issues before posting this of course. As a matter of fact the possible rfi leftovers from past setup are now completely gone and fixed. 
So this seems to happen only on the K3+MK2 setup and 'never' on the IC-756 pro2 + Rigblaster one.
Note that when using 2x 756s and Rigblasters for way over 40,000 contest qso this never happened.
 
I thought it may be an so2r related issue but a good friend running k3+mk2 on one radio only has experienced the same problem.
 
Anybody out there using the same equipment has seen this in their shack?
 
Many thanks  73,
 

Fabi  va2up
http://sites.google.com/site/va2upcontesting/