I have a 99 c230 and have had this problem ever since i changed the battery about 6 months ago. Basically, the windows, the central locking system, and the mirrors quit working. I disconnect the negative battery cable for a few seconds and everything starts working again for a few days. Then the same problem happens again. I have gone through this process roughly once a week for the last 6 months and would like to know if anyone has any idea what the problem is.

Thanks so much for the help.