Hi,
you should have asked in the Logic Pro Forum, not in the Jam Packs Forum 🙂
1. Now, does this problem persist even in other projects or just in the project you are working at? Did you try importing the song/track/whatever into another project?
2. Repair your permissions (HD Utility)
3. If the problem persists in other projects, backup and then trash the preferences of Logic. You find it in (user) /library/preferences/com.apple.logic.pro.plist. Logic will rebuild this file with standard values which may solve the problem.
4. Re-Post this question in the Logic Pro forum!
Fox