Well, I tried all that, but the generated password on my dad's machine is still different from the one generated on my machine. We compared all the settings and they are the same on both. We are both on the same web site, we both highlight the same account in the account specifix options, use the same MPW, but the passwords are different.
The only difference in the two installations seems to be that mine was a fresh install string with 0.8.*, whereas my dad's was upgraded from 0.6.*. Also, I had removed PM on his machine and reinstalled 0.8.7. I didn't remove the profile, though.
Any idea why the passwords would be different ?