Trashing DAE preferences normally fixes this problem. Exit ProTools completely, then navigate to:

C:\Program Files\Common Files\Digidesign\DAE\

There, right-click the folder "DAE Prefs" and delete it.

If this does not help trash all preferences using the procedure below:

(Start by exiting ProTools again)
1. Go to: My Computer > C: > Documents and Settings > (your user name) > Application Data* > Digidesign. Delete the file entitled "ProTools...vX.X Preferences.PTP" (this may be either ProTools LE or TDM, and any version, such as 6.4 or 7.1).
*If the Application Data folder is not there, go to: Tools (in the menus at the top) > Folder Options > View, and select "Show Hidden Files and Folders."
2. Go to: My Computer > C: > Program Files > Common Files > Digidesign > DAE. Delete the entire "DAE Prefs folder."

Empty the Recycle Bin after trashing preferences and/or databases.