I did a post about this. Do a search of "finally, how to fix those digital odometers", or something to that effect. They start messing up (blinking at first, and eventually going off for periods of time) because the solder joints at the odometer crack and make sporadic contact. Re-soldering them should fix your problem. Of course I'm assuming that your alarm has nothing to do with it, that it just happend to start doing it at that time. I don't see how the alarm could affect it, of course I could be wrong.