Here's the fix: Seems the database gets corrupted on Windows.

For XP (Assuming C: is your boot drive) go to Cocuments and Settings[Your Login Account]Local SettingsApplication DataPentaxDigital Camera Utility 4

and delete the Temp_Data directory entirely.

For Windows 7, go to the same folder under C:Users[Your Login Account]Local SettingsApplication DataPentaxDigital Camera Utility 4

and delete the Temp_Data folder.

The app should restart and work fine...until you change the source directory for your pictures or some such thing.

It is a useful application, especially for PEF files, but Fast Stone Photo Viewer is free and work much better and supports the RAW files from most camera models.