Practically every multimedia application installs its own DirectShow codecs and with all the 3rd-party codec packs out there it's pretty common to have corrupted registry entries for DirectShow components. The GSpot utility <http://gspot.headbands.com/> will detect problem codecs and filters (highlighted in red under List Codecs and Other Filters), but the Re-Register and Un-Register Filter contextual menu commands usually fail to repair or remove the corrupted registry entries.
The K-Lite Codec Pack <http://www.codecguide.com/> includes a K-Lite Codec Tweak Tool with several registry repair options:
- Detect broken codecs
- Detect broken DirectShow filters
- Register quartz.dll
- Fix non-working system sound
Since not everyone is inclined to install a codec pack just to repair their DirectShow registry settings, it seems that these functions would be a great addition to a future release of CCleaner.