Cubase >< Rewire losing Connection

Hey
I tried to Rewire Cubase 5.5 32bit and Max MSP 5 32bit on a Windows 7 64bit. Works nice - but just for 100 Seconds and then loses Midi Connection. After resetting the drivers it works again for 100 Sec.
Same Issue on a different Windows 7 64bit with Cubase 7 Trial and Max MSP 6 64bit Trial. Works for 200 Seconds this time.
same Problem found here:
https://www.steinberg.net/forum/viewtopic.php?f=19&t=14680
and here:
http://cycling74.com/forums/topic.php?id=42344
Anyone an idea?
Thanks
Joel