I had a similar experience: I have a permanent dynamic lighting system installed in a food hall / night club. One day about a year after installing the owner called to tell me a fixture was on the blink. The following day, another, the following day, more, but different ones. This was worrying as all the hardware is custom and would be very hard to source replacements for. We investigated lightning strike or other power surge related to construction on the block, water damage, etc. Long story short we found out that the new cleaner, who was VERY VERY thorough, was pulling out the server rack to mop behind it nightly and straining the cat cable terminations.