I bought a 04 x5 with a leaking sunroof and I had I kinds of problems that I chased. However what the cause of many of my problems was the roof leaked into the glove box and it had leaked into the fuse box. When I pulled it out I could see corrosion inside the on the circuit board. I found one on ebay for $32. The best money I ever spent.

One other thing to try is unplug you ABS and drive it. I have found that there are alot of thing attached to it. That is a easy test and it doesn't cost anything.