Alt+tab not functioning

I googled the above phrase (thread title) and came across this page http://forums.techguy.org/windows-nt-2000-xp/626602-alt-tab-not-working-correctly.html and followed the steps outlined there to no avail. Everything that I found in my search related to specific problems with certain programs not allowing alt+tabbing from them, but otherwise it was functioning normally. Tabbing is fine, both alt keys are fine and functioning well, and I just cannot figure out why I can't alt tab. I've restarted multiple times, I've system restored back, I followed the above listed thread's direction for regedit on "Coolswitch" all to no avail. Halp please.