window previews (thumbnails) is not available

[Guest]

For some reason when i move my mouse over a open program in the taskbar does
not show the thumbnail preview, it used to work just fine but now it does not.
I am running Windows Vista Home Preview with Aero enabled. when i
right-click on the taskbar to enable this option it shows gray out. I dont
know whats going on!

Thanks for your help!

 

[Guest]

I finally figured out what it was. I rarely use itunes, but was playing with
it one day and turned on the iTunes toolbar on the taskbar. Today, just by
chance, I saw it and removed the iTunes toolbar (right clicked taskbar
expanded Toolbars, then deselected iTunes) and BOOM. Back to normal. I
appreciate all the help guys, be sure to pass this on in the future just in
case someone as picky as me is wondering why their taskbar isn't transparent
anymore. Since iTunes does not support Aero... it disables the transparency
in the taskbar.