This might occur because of the corrupted Windows registries.
Delete and reset the Language templates preferences registry key as follows:
1. Open registry editor (regedit) and expand the path 'HKEY_CURRENT_USER\Software\Xilinx\ISE\11.1\Project Navigator\Language Templates'. Under that you will find "Preferences". Right-click it and delete it.
2. Open ISE, go to the Edit menu, and click "Preferences...".
3. In the category, select "Language Templates".
4. Uncheck "Use Project Directory" and click Apply. If it is already unchecked, then check it. This step is for recreating the Preferences in the Language templates registry.
5. Close and reopen the ISE window and try launching the Language Templates.