Opening A Logic 4.8.1 Song In Logic Pro 7.1.1 - Problems. Help! Options

[Dave Knife]

I am a long term logic user moving to logic pro.
Much of my work is still in Logic 4. I use a combination of Audio and midi.

When I open a logic 4.8.1 song in logic pro 7.1.1, I experience crazy midi behaviour.

For example, I record a part on the EP88 electric piano.
When i listen to what i have recorded, it does not make any sound at all. Then, after double clicking on the "reorganise memory" function on the transport window, it will sound. This seems to be the only solution.

If I then attempt to edit what I have recorded, logic plays the part in some random pitch - forcing me to reorganise memory each time I do any editing in the matrix editor! Progress is painfully slow - help!

My system is :

LogicPro 7.1.1
OSX10.4.6
Dual G4 1.25mhz with 2gb ram
MOTU 828mk2 with latest drivers