Routerbord lockup

HI

I had a routerbord 532 lockup 4 times in one week. It would work for a day and then just freeze up. It keeps the clients connected and I cannot acces it via mac-telnet through either lan or wireless.

After the second time it happened I replaced the routerbord and wireless cards and the exact same thing happened.

I have more than 200 of these routerbords with similar configuration on highsites but never had something like this happen to me.

Is it possible that somebody can hack a Ap and force it to go into a lockup? And if it is how can it be prevented?

Thanks