Does inter-CPU variability exist in NONMEM??

Dear all I’m a newbie in this field practicing NONMEM using a few sets of bioavailabilty data. 2days before, I managed to make a model and got to get some parameters. Though I couldn’t sure about it due to my poor background, they(parameters) were quite similar to those in a paper. Anyway, the thing was, the results were not constant in a single NMTRAN file. I’ve struggled for a few days figuring out what the problem was, but I couldn’t get the first result. After I had run the same control file with the same data in another PC, surprisingly, I could find that the parameters were not the same as those from the prior PC. This had AMD X2 250/2G DDR2 DRAM(Samsung)/windows 7 32bit and that had Intel i870/8G DDR3 DRAM(Samsung)/windows vista 32bit. Both had NONMEM 7/gfortran(in NONMEM7 CD). My friend, a developer, said that It didn’t look like the problem of the processors but of the compiler. Because I’ve had fairly good relationship with AMD for long, I want to believe he’s right. Is anyone here who ‘ve met a similar problem?