What is error -10180?

... and how do I make it go away?
I have just upgraded my iMac to Leopard and now I get most of the apps failing to open! I am told there has been an unexpected error (-10180)

I have repaired permissions ... but that hasn't really solved anything

Shift on startup seems to solve the problem (does this stop all startup items or just apps in the login panel?)

Any ideas please? ...

at least I have my MBP!