For some reason Logic crashes when I try to open up preferences. It never crashed in 10.3.9, 10.4.3 or 10.4.4. I think I remember using it in 10.4.5 as well but now it just wont let me open up preferences. The versions says 7.0.0 although I got 7.0.1 installing now but I remember it crashed with 7.1.1 as well. I reformatted my HDD cos of this....any solutions?

Have you trashed the pref files? audio cache? and have you done the:

Pro Application Support Update 10.3.9)
Pro Application Support Update (10.4+)

3 things. 1.) use setup manager to create a new set of preferences.

2.) zapp your pram, when you load an new OS some settings are stored in Non-volitle RAM (battery backed up)

when you downgrade OS, you may still have settings from the newer OS stored, that may or may not work with the older OS.

3.) If that doesn't work go to the Apple site and download instructions on how to reset the Power Management Unit
(PMU) for your specific machine. That will set all Non-volitle RAM to it's default condition.
If you have a laptop, I suggest taking it to a Apple Store or certifieed repair point.

I ran into this problem when I upgraded the drive in my Powerbook. I loaded 10.3.0, but settings from 10.3.7 were in my PRAM. Couldn't stay connected to internet long enough to download updates. I put my old driv in a firewire enclosure, booted from it and every thing was normal.

I think that Apple never really considered that someone would want to downgrade their OS.

Downgrade OS X? When your life can be ruined by a security update of the latest Quicktime? You're kidding?

The trouble is, it's mainly the music community who faces these issues unfortunately.

Solution: ALWAYS have a clone of the working system handy…