Desktop Slideshow Theme stopped switching images

That basically says it all. When I installed Win7 Home Premium 32 bit I installed some desktop themes with images that switched. Cool. After a while I downloaded some picktures and created my own. I have them set to switch every 15 minutes. THe past few weeks, I noticed that they were no longer switching. I can manually right click the desktop and 'bump' it to go to the next image, but it will no longer switch on it's own. Any suggestions?

Try this solution:

Type edit power plan in the Start Search box, and then click Edit power plan.
Click Change advanced power settings.
Desktop Background Settings > Slideshow > Make sure it's set to "Available"
If that was your problem, it should be working now.

Some more solutions from winvistaclub:

If you are unable to change or display the wallpaper of your Windows 7 or Vista desktop, try this :

Open Control Panel > Ease of Access Center > Make the computer easier to see.
Ensure that Remove background images (where available) is unchecked.

Save, Apply, Exit.

This should help !
If it doesnt, try this:

Run regedit and navigate to the following key:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies

Then right click on Policies > New > KEY > name it as “ActiveDesktop”.

Next in RHS, rt click > New > DWORD > name it as “NoChangingWallPaper” .

The DWORD value 1 will restrict change in desktop wallpaper. To allow change give it value as 0.
Reboot.