Sleep and Photos screensaver

I seem to recall many moons ago, reading here that if there were "too many"
images in the designated folder in Photos screen saver, the computer failed
to turn off display and sleep. Is this still the case?

I had Ribbons as my saver, Wait = 10 minutes, Turn off display = 20 min,
Sleep = 30 min. Worked perfectly.

Change to Photos, designated folder C:\Users\User Name\Pictures\, same Power
settings; Wait OK, no turn off display, no sleep.

Any gurus out there any ideas? any "missed" updates? any other settings
apart from the obvious in Control Panel - Personalization?

Vista Home Prem, SP2, all other updates except IE8.

--
Delboy

A common mistake that people make when trying to design something completely
foolproof is to underestimate the ingenuity of complete fools.

Douglas Adams