Error dialog box FIXED by moving Memory Slot Utility to another folder. On reboot, the dialog box no longer appears.
Like others, I've gone through variations of this problem with Memory Slot Utility in the past:
(1) months ago I added 8GB RAM (from Apple!) to preinstalled 8GB RAM (from Apple!), positioned in proper slots, and had Memory Slot Utility report new memory was configured correctly on EVERY boot; once was fine to inform me, but every boot?
(2) as a last resort, I moved Memory Slot Utility from HD->System->Library->CoreServices to a newly created folder, and the problem went away.
To my surprise, I found with OS X 10.7.4 upgrade, Memory Slot Utility had returned from the dead, this time giving not the old "All is going well" message but the one we've all been reporting. After moving the new Memory Slot Utility to a different folder, the problem is solved.
Not happy now, and never was, with Memory Slot Utility.
But you've all been a help. Thanks.