macbook pro 2,2 ghz identification problem

Might be another way > How to find the serial number of your Apple hardware product

A label inside the battery compartment may give you the machine's original serial number. But the reason you don't see one in "About This Mac" is that the machine's logic board has been replaced, and the replacement board's number was not entered into the place, wherever it is, where "About This Mac" expects to find it. So the number in the battery compartment will no longer match the one on the logic board even if you can find both of them. The machine has, in effect, had an identity transplant.

What is the reason for your interest in knowing its serial number?

EFI Boot ROM and SMC are at the latest version.

Have a look here http://support.apple.com/kb/HT1237

Stefan

In most cases when Apple replaces a logic board, the technician will flash the new serial number into the appropriate register and it will show up in "About This Mac". I believe Apple techs are also supposed to remove the original serial number label. Neither of these things happens every time, unfortunately, so it isn't possible to tell with any certainty whether a LB has been replaced by an Apple tech or by someone else, possibly the machine's previous owner.

If you were given the discs that were originally shipped with the machine, one of them contains the Apple Hardware Test for it. Running that might give you some measure of confidence in the machine. If you don't have that disc, you won't be able to run the test. AppleCare might be able to supply a duplicate disc for a fee; call and find out.

The ultimate test of your hardware, of course, is how it behaves in your daily use of it. If it seems to work OK, it probably does. But a certain amount of risk is just part of buying a used computer: that's why they cost less than new ones.