That's slightly different. The e34 and e30 have a code built into the OBC that people can use for anti-theft security. It requires someone to punch in a code in order to start the car. Somethign I believe Komodo is trying to build for himself right now. But nick you also mentioned the radio code, which my e34 has aswell. This is a code required to be put in, in order to allow the radio to work. Many of you have disconnected the battery for longer periods of time and realize that after you reconnect your battery you are required to put this code in for your radio to function.
But I don't see how she couldve put the code in incorrectly if it works some of the times. I wouldve guessed amp too because I know some BMWs also have that problem. Maybe just a shitty connection from harnesses/wiring.