So, you’re reading all sorts of good stuff in the Library in the Exchange TechCenter, when, all of a sudden, the Table of Contents in the left-hand pane disappears! Where the #*$! did it go? Calm down, and hit T on the keyboard. Whoa! It’s back! Such a relief. But, hey, now you’re thinking that all that extra space was kinda cool when the TOC was gone.you don’t need no stinkin’ TOC. What to do? That’s right, just hit T! It’s gone again! Hit T! It’s back! Go forth and amaze your friends.
Check it out! http://technet.microsoft.com/en-us/library/aa996058.aspx