My volume box was uncheckable the first few times I tried to fix this problem. But after searching "volume mixer" in the Windows Help and Support through the start menu, I was able to open up the volume mixer. Then the next time I clicked on the taskbar properties I was able to click the volume box. Maybe this will help out -- I'm not expert, but the mixer may have to be a recently used program to make that volume box clickable.... or something like that. :)
Missing Mixer
My volume box was uncheckable the first few times I tried to fix this problem. But after searching "volume mixer" in the Windows Help and Support through the start menu, I was able to open up the volume mixer. Then the next time I clicked on the taskbar properties I was able to click the volume box. Maybe this will help out -- I'm not expert, but the mixer may have to be a recently used program to make that volume box clickable.... or something like that. :)