DAW to DAW compatibility issues - PC to PC - both X3, Win7 64, different Midi setup...

Hi Y'all.  So i have been unable to resolve a problem where i have two Win7 DAWs, both nearly identical, both running the same software - X3, plugins, yet when i move from the one DAW to the other in another studio, some of the Virt instruments get mismatched to the wrong midi tracks - usually requires going through all virt instruments and related midi tracks and sorting them each time.  I know lots of folks switch DAWs while working on Sonar projects without having this issue.
 
They both have RME UCX as interface.
 
The only real difference between DAWs is that one has an extra midi card for extra midi capabilities.  When i load a project from that DAW into the other DAW, it finds the missing midi card and i select 'OK' or 'ignore'.   i'm wondering, is this is the source of the problem?  It's a cheap midi card - i could get another one and have the same cards on both DAWs - will that fix the problem?  TIA.
 

I agree, I have a total mess of computers, different versions of Sonar, different audio interfaces, the works. I save all my work in a folder for each project and the CWP icon and Audio folder are contained in there. I also save as MIDI files too as a safeguard. 
If I move that folder to another computer it always opens with a few minor hickups. 
 
If you open a project that was created on a newer version of Sonar on an older version it will warn you that some things might not work,  but it still opens and runs fine. So CWP files seem to open on all versions of Sonar I have from Sonar 8.5 up until now. And Home Studio too. 
 
It might complain about a missing plug in or VST. They will show in the effect bins and synth rack but grayed out. So I at least can tell what they where and either go find them or swap for something better. 
 
And yes it might warn about missing Audio and midi ports but this doesn't change the project. All my projects play exactly the same no matter where I play them. Only missing plugs or synths would change this from happening. But I've never had it change synths or patches if they are available and load up. It even seems to grab any changes I made to the synths. Very rare it doesn't do this. 
 
The screen size will reflect the size of the project it was saved on, I can tell  right away that a project was saved on my laptop because it's about half the size on the screen.  
 
But right now I keep both my laptop and desktop more or less synced with the same versions and plugs etc. Each uses a different audio interface which makes no difference at all as both have more or less the same connectivity. The Tascam just has more inputs. 
 
What I would try is selecting NO midi outputs to the outside world and save the project. That should take your midi interface out of the equation. 

Port numbering of soft synths will start with the next available number after the port drivers enabled in perferences. This shouldn't be a problem in most cases because both track outputs and synths will be offset by the same amount in any given environment. The exception might be drum maps which route by port number and won't be automatically re-mapped IIRC.

Thanks, Cactus Music, brundlefly.  Great ideas to check. 
 
Cactus Music, regarding versions, now i'm wondering how often it has been because one machine has DimPro 1.x and the other has DimPro 2.x.  I can see if installing 2 eliminate the problem.
 
Brundlefly, re missing plugins/list - the drums (EazyDrummer2 ATM) are the only plugin i know for sure that always work fine between machines - maybe because it often gets first in line in the .list'.