Dear SPMers: I am replying to my own message as, for the moment it appears that I have solved my issue by repairing permissions with Mac's disk utility and reinstalling the latest version of SPM 8 (Mac Intel 64bit) on my iMac. I have no idea what caused the problem but I am concerned as it came up not only on my iMac but also on my PowerBook and my research assistant's iMac. Therefore I am positing the solution here. Cheers, Michael