Microwave cross talk?

[bhnjr@xxxxxxxxx]

On a recent installation we used 2-microwave/pir, ceiling mount units
in a commercial bank lobby (about 40'x80').  The units are spaced about
20' apart.  They seemed to work well at first, but soon started to
false. Could it be that the microwave units are setting up some kind of
cross talk between them selves?  Thank you.