Cubase/audio interface change problem

[enigmacrypt]

Hello, could anyone help me with this problem?

I recently upgraded my audio interface from the m-audio delta66/omni studio to the RME Fireface 800. I also upgraded from Cubase sx 2.2 to sx 3.1. Now when i try to open up cubase projects I did previously (especially ones that involve additional buses) I get a 'serious error' message. I can see that the old project is trying to access the old m-audio delta66 as i get a pending audio connections pop up. But by that time even changing the audio connections doesn't help because things are all messed up due to the error message and it needing to close cubase. I have loads of half finished projects that i can't open and i'm not sure what to do. Any ideas? Thanks in advance for any help with this.