S60 AWD electrical problem
 

I own a 2003 S60 AWD and have had a wonderful expereince with this car until this past summer (JUly 06). The car displayed several different warning codes (BRAKE SYSTEM FAILURE, ELECTRICAL SYSTEM FAILURE), and after pulling over, the car would not start. The dealer replaced the differential module, and the central electronics module (this repair was determined necessary by an engineer from Volvo, who was called in by the dealership as they were stumped by what to do to fix this). The car was running fine, until last week, when the same problem happened again (warning codes, etc.). I was out of town so the car is at another dealership, and whose mechanic has determined that the car is fine. Does anyone know of a problem like this? I drive around with a 2 year old on city expressways and I feel very uneasy about driving this car now. The car is under warranty and I was also curious if Volvo replaces or exchanges unrepairable cars? Thanks!