We had a couple of technical issues with the guider tonight.  At ~00:45, while observing a field on the edge of the LMC, the guider signal drifted by ~1 arcsec from the beginning to the end of 3-4 exposures, leaving elongated PSFs in the images.  We chalked this issue up to the trouble with guiding in a crowded field with DECam.  Affected images are 518192 - 518195.  However, the problem reappeared while observing the next field, which was uncrowded.  The guider signal would again drift in +RA and +Dec, as can be seen from the Guider telemetry plots, and produced elongated PSFs.  Affected images are 518219-518222.  We tried decreasing the guider exposure time and closing the windscreen, although the wind was only moderate, 10-15 mph.  Closing the windscreen may have done the trick in the end.  At the time, however, it appeared as though the guider was sending signals to correct telescope drift, but the TCS was not responding appropriately.  Humberto suggested that a network issue could have produced the problem, or it was just the wind.