I've just come up against the same problem moving my previously working OS Commerce V2.2 MS2 site to a new server with PHP5.
Turned out that I needed to turn register_globals on in the php.ini file.
Having applied all of the changes to V2.2 MS2 I could find as part of my server move work (Updates 051112, 051113 & 060817) I'd been hoping that the need to turn on register_globals was no more, but can anyone tell me if this is still a normal requirement for os commerce?