I had similar problems with some programs (I don't recall if FLS was one of them) when migrating software. Reinstalling the software generally solved the problem. I'd suggest first backing up ~/Library/Application Support/FontLab and ~/Library/Preferences/com.fontlab.fontlab5, then deleting the following:
~/Library/Application Support/FontLab
/Library/Preferences/com.fontlab.fontlab5
/Library/Preferences/com.fontlab.licenses.plist
/Library/Application Support/FontLab
/Applications/FontLab Studio
That way you're doing a clean install with no residue left over from your old install. If the problem goes away after doing this you can restore your old preferences and any customized files you may have created in ~/Library/Application Support/FontLab
André