Cubase >< Rewire losing Connection

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:
and here:
Anyone an idea?