Halion One rpoblems with old projects

I finally upgraded to Win 7 and went from Cubase 4 to 6.5. I installed Hallion One, but it’s not working very well. In some old projects I can’t even find the sounds. In others I can. It seems it might be related to how many synths I am using; more synths causes problems. I only have 2 megs of RAM installed - is that my problem?
I’m wondering: if I uninstall Halion One, would Cubase reassign those channels to Halion SE? Any tricks to share on this?

No, Cubase can’t reassign these travks to HALion Sonic SE tracks. Isyour HALion One (and its library) up to date?