The micro is receiving the serial data on a port (its not RS232 data)

By that do you mean you are receiving data on, say, P2.5 (or whatever), but that you are not using the built-in UART?

If the data is wrong then the code crashes and the control goes to some unknow address where it never returns.

Heheh, I hate it when that happens.

all comparing statements do lead to a definite address and all sub routines do return and all pushes do pop in order. ?

What is the difference between "good data" and "bad data"? What is "broken" about the bad data? Are the bits being received wrong (communication-level error) or is the communication itself okay, but the data is logically wrong (i.e., you received a byte 24h instead of 36h)?

Craig Steiner