Start recording the time of day and day of the week and duration. Keep a log to see if there is a pattern. You may have a CBer with an illegal amplifier in the area. Turn the sensitivity on the receivers down to the minimum needed to make your system work. You do not need to control it from down the block. Turn it to minimum. If it works there, leave it there and track the interference. You should contact URC after you have gathered more information.
When you have interference, you could try turning off one circuit breaker at a time at your electrical panel to make sure that the interference is not coming from inside your home. If you or your neighbors have ionization type air cleaners, they may put out random RF. Think of Marconi and his spark gap transmitter. I have seen problems with some older security system wireless receivers caused by the spark type pilot light starters on some furnaces, although this should be of short duration, only while the furnace starts.