This is a bit of an open and shut post as I've found the solution, but it's a bit obscure so thought I'd stick it up here in case anyone else had this problem.
After installing the 10.5.8 update, Suitcase Fusion (am using v12.1.7) would bounce once in the dock and then abort. I called Applecare (who had surprisingly not heard of this Application) and they suggested moving the com.extensis.suitcase.plist preferences file to the desktop and restarting my Mac (essentially resetting Suitcase Fusion).
I didn't feel that re-installing Suitcase Fusion was going to do any good, so said thank you and went back to scouring Google …and lo, the solution was there all along…
The problem had something to do with the *Bonjour Name* of my Mac. Apparently, if you have any special characters in your *Computer Name* or if it exceeds 20 characters, then this causes a problem with the *Bonjour Name* and then consequently with Suitcase Fusion …simples.
See? …told you it was obscure.
1. Open *System Preferences > Sharing*
2. Change the *Computer Name* to something shorter with no spaces or special characters, something like MyName-MacBookPro
(NB. If you're not logged in as an Admin user, you'll need to click the lock and enter a password first)
3. Click Edit… to ensure that the .local name is the same
4. Close *System Preferences* and restart your Mac
And Bob's your Uncle, that should do the trick :o)