Logic is currently having a problem working when more that 1 Gigbyte of RAM is installed on a Mac. There is, however, a trick to making Logic work when the Mac has slightly more RAM than 1gig:

1. Lauch Logic
2. Click on the Finder.
3. From the Apple menu, choose "About this Computer"
4. Make note of the size of the "Largest Unused Block". (Say , for example, its 1,200 MB).
5. You'll want to allocate an additional 201Mb of RAM to Logic:
a. QUIT Logic and all applications
b. Click your mouse ONCE on the application LOGIC
c. From the FILE menu, choose Get Info -> Memory
d. If (for example) the Preferred size is 80,000 , raise it to 281,000
e. Close the Memory information window, and resume using Logic.