Car: 1996 S420 (W140)

For the last 3 or 4 months the ABS & ASR lights would suddenly come on. Each time it turns out to be the fuse controlling the brake light/cruise control/ABS circuits. When I replace the fuse, all is ok again for 2 to 3 weeks. I've already replaced the stop light switch.

Anyone had this happen to them? I don't know where to look.

Thanks.