It sounds very much like your processors aren’t exactly the same between the two boxes. (Keep in mind that there were atleast two cores that I know of for a 3.0G P4 that I know of) Unfortunately, lately it seems they are producing new functionality in newer cores of teh same processor speed that seems to “break” virtualization. If I recall correctly the differences lie in teh SSE/SSE2/SSE3 and NX instruction sets between the different cores.
There are articles on VMware’s site about this, but <a href=”http://spininfo.homelinux.com/news/VMwarewolf/2007/06/20/Are_your_servers_VMotion_Capable_”>here</a> is a good intro article that should get you on the right track. These articles walk you through turning off the previously mentioned instruction sets for the VM (you’ll have to power off and restart each VM to complete this)
**This is definately something you want to consider carefully before you do this in a production environment.**
Hopefully that helps answer your question.