PRB: HTML Help Viewer Causes Access Violation

After running the HTML Help update program, Hhupd.exe, an access violation occurs when trying to view any .chm files.

The access violation may not happen immediately after running Hhupd.exe.

The file Hh.dat is corrupt.

Delete Hh.dat. This file is located under the WINNT directory on Windows NT and Windows 2000 systems, and under the WINDOWS directory on Windows 95, Windows 98, and Windows Millennium Edition (Me) systems.

Reinstalling Hhupd.exe or Internet Explorer does not fix this problem; however, it could help if the errors you are getting are not caused by Hh.dat.

Hh.dat is a database file that saves such session information as the window position and favorites for the HTML Help viewer. The database file is automatically updated every time the HTML Help Viewer is used. If the database file does not exist, it is re-created. When updating the HTML Help viewer, the information in Hh.dat is not necessarily compatible with the new viewer, which can cause it to become corrupt. Deleting the Hh.dat file when Hhupd.exe is run is a good practice.

NOTE: Deleting Hh.dat causes the "favorites" settings to be lost. However, running Hhupd.exe makes changes to the HTML Help Viewer that could render them unusable.

For additional information, please see the following article in the Microsoft Knowledge Base: