OSX/App relationships



I have been attempting to remedy a long-running slow-boot problem all day. After running several maintanence tasks (repair permissions, cron scripts etc.)
I have discovered that dreamweaver, fireworks and flash (MX) will no longer launch, (Director and Freehand however, will).
The icons for the 3 apps have changed to white document icons, and it appears as if OSX no longer recognizes them as apps, as when i attempt to launch any of them, finder prompts 'There is no default application specified to open the document 'Dreamweaver MX 2004', or whichever of the 3 apps I choose.
Does anyone know how to fix this without a reinstall?
In windows I would attempt to reassign the .exe extension to refresh the ext relationships but gather that OSX interprets these differently.

I imagine this has no bearing but the offending apps as MX 2k4 running on OSX10.3.9 on an ibook G4 (1.07ghz, 1.25GB, 40GB)

All advise appreciated,