i dont know if this is similar to what you guys are experiencing, but a coupla months ago i was drivin home with my low beams on and i was starting to get onto roads without street lights so i flicked on the high beams...
exactly as i flicked them on the car seemed to die....cd player off,lights off,speedo etc. dead,tention of accelerator gone...all for about a second,then it was normal again....
it did this all the way home,really freaked me out...then when i got home the power windows wouldnt work to put the windows up,the interior light didnt work and the central locking wouldnt lock the doors.
so i started it back up (took a few tries) and let it run for a few minutes.
after that everything worked fine again...next day took it into autobarn and got a battery and alternator test, the test said good battery and the alternator was charging at the right voltage...i thought that was really weird so we did a second test..this one said replace battery and alternator was same as before...
anyway,picked up a new battery and some sandpaper while i was there and put the newie in after givin the connections a bit of a sanding..its never done anything wrong since.
i guess my point is that dodgy batteries can do really wierd stuff to you cars electronics.