PowerSDR interferes with Meinberg NTP

PowerSDR appears to interfere with the Meinberg network time protocol (NTP).  Has anyone observed this?  When running WSJTX digital modes / JT-65, it is important to have the computer time synchronized.  I observe that it is well synched when I first start the radio and WSJTX.  I often leave it running all day and notice that the time synch slowly drifts out of synch.  After much experimentation I find that I can resynchronize it by briefly stopping and restarting PowerSDR.  Stopping other programs and restarting the Meinberg NTP do not help.

I am running:

brand name quad core PC with Windows 7 64 bit home premium

PowerSDR 2.7.2

Flex 5000A

WSJT-X v 1.1

Meinberg NTP

Thanks,

Thurman AA5KK