Same thing happened to me last week, only it required disconnecting the battery for a hard reset. The wipers stopped working-- there was some sort of relay that had gotten itself mis-set.

This was the BMW, right? Welcome to the wonderful world of German car ownership. The electrical glitches add character. :)

A couple years ago, my engine (in a BMW) started acting funny one day -- it wasn't staying at steady rpm's while idling, and it just sounded/felt weird while driving. I drove like that for a little while, hoping it would clear up. When it hadn't after a few minutes, I turned the car off and restarted it at a stop light, and then everything was fine. I also assume that was an issue with one of the computers.

However, that's the only seems-like-it-was-due-to-a-computer issue I've had with the car in eight years (that I can remember).

There is a thing (another computer) you can put in your car, connect to your on board computer, and get error codes, and performance results (instantaneous MPG for instance). It is called a Scan Gauge II, runs about $150.