Windows 7: Windows 7 - some toolbar functions lost

Greetings all,
I have a weird issue. I am running Win 7 x64 ultimate and this problem has persisted through one vista upgrade a two windows 7 fresh installs, each time I used a different distro.

Here's the problem:
After about 24-48 hrs I loose the capability of some buttons. the two areas are the selections next to the shutdown button (switch user, lock, reboot, etc.), I see the buttons but when I left click on them they just simply disappear. This holds true when I go to my shortcut button on my toolbar and click the chevrons next to it, I see all the folders, but when I click on them they just disappear.

I can fix this each time with a reboot, but this is driving me crazy!!!

thanks for your help in advance!
akatrauma