'01 Tahoe - Cruise Control Problems

the cruise control will turn off after 5 to 20 minutes ONLY when my lights are on. cannot turn back on unless shut off the vehicle for awhile and don't use lights. cruise works fine in the daytime when the lights aren't on. first noticed problem only when pulling my boat trailer and the lights were on. now prob acts up anytime the lights are on and no trailer. i've noted no other electrical problems or symtoms. i've replaced both rear running/park lights and put in a new battery.

please help!