Thanks Zane,
Ran both “repair permissions” (which I do regularly) and Diskwarrior 4.2 booted from my 10.5.8 clone, (which I run when I have performance issues).
DiskWarrior did speed things up. No major problems found.
Desktop still invisible in my user account.
I checked back at my archived CCC files and the invisible desktop started almost a year ago.
I think it might have begun when I installed Basilisk II, which is an old Mac OS emulator. For some reason the program installed in an “applications” folder that was in my user account folder. No other apps were in there. The folder actually had Apple’s app icon on the folder image. I moved Basilisk II to the regular apps folder and deleted this misplaced folder.
Everything on the Mac has been running smoothly. No serious problems. Safari crashes some times when it deals with flash media. Other than that I only run into problems when I over tax the limited amount of ram. FCP runs fine. QT runs fine. I never noticed that desktop was invisible since I either access it from the desktop, the dock, or the sidebar. All these behave normally.
OSX 10.5.7; MAC Book PRO (EARLY 2008); Camcorders: Sony Z7U, Canon HV30, Sony vx2000/PD170, Canon xl2; Pana, Sony, and Canon consumer cams; FCP certified; write professionally for a variety of media; teach video production in L.A.