Camera locking up?

I sold a friend my digital camera because i needed something smaller.. it was working PERFECTLY when i gave it to him.. just i havent used the rechargable batteries in a while, i was just using AA"s.. Now he has been saying its locking up, which i cant understand. I think he might just be bsing becuz he might be having second thoughts on the camera.. Or if you guys think he is telling the truth, what could be some reasons why it would be locking up? It was working perfectly when i got it, so its not firmware, and i told him to change the batteries, and he is supposedly saying it still locks up.. This locking up isnt every time, just once in a while, which wouldnt make sence.. its not like a computer where it would slow down or anything.. pleease help me... I dont understand how a camera could "lock up", ive never experienced this, so i want some input if he is bsing or not..

he says when he is in the menu of the camera itself, it is locking up. He said it was as if someone had a remote and was controlling the camera when he was trying to do stuff..

i dont know if he dropped it, he might of, but hes obiously nto going to admit that to me.. but he hasnt complained in a few days so hopefully all goes well..