Greets - I'm a Logic 6.1.0 Platinum user on 10.3.9

I downloaded the Logic Pro version (that is, version 6.4.3) which is found via:

http://www.apple.com/support/emagic

but i get the msg "Logic has unexpextedly quit" every time i open it.

I went and downloaded Logic 6.3.1 .. but same story. Both of these led me throught the usual installer processes btw.
My previous versions of 6.0.1 and 6.1.0 still load up fine.

So, do these updates need to be 'linked' or 'recognized' by the previous versions
somehow?
Anyone had good/bad results from downlaods on the Emagic 'Legacy' page?

thanx if you can help