I have experienced this same problem, but it seems to only happen when I'm using my car charger (the iGo universal charger from RadioShack). The BB's backlight will turn on every few minutes for no apparent reason. This does not seem to coincide with any data transfer, incoming/outgoing messages, or other network activity like entering or leaving the coverage area. I'm using the Sprint-branded 7250. BBLight does not fix this activity, and in fact it seems to happen more often since I installed BBLight.