I was in training a few weeks ago (WMS 2008 new features) and found that no matter what I did I was not able to get hotfix KB929182 installed on my Vista lab machine. The hotfix would act as if it installed correctly but the affected DLLs were not updated. The title of the KB in question is: “FIX: You may experience issues when you use Windows Media Encoder 9 Series on a computer that is running Windows Vista“. After having a number of CDNs report this issue, we investigated further and another engineer on my team was able to figure out the steps necessary to get this KB to actually install as expected. We think we know why this is occurring but we are still investigating. The steps below should help you to get around the issue until we can get the patch updated (assuming our requested changes are accepted).

From the Control Panel, Program and Files

1. Remove Security Update
        Security Update for Windows Media Encoder (KB954156)

2. Remove Hotfix
        Hotfix for Windows Media Encoder KB929182

3. Remove current installation of the Windows Media Encoder 9 Series

4. Restart the system (DO NOT install updates)

5. Reinstall the Windows Media Encoder

http://www.microsoft.com/downloads/details.aspx?FamilyID=5691ba02-e496-465a-bba9-b2f1182cdf24&displaylang=en&Hash=Q7YOichtn5uaPziFse1ENeP0pr3Zm3uDvElbQn2p9UGArhz5hMZIta1wqWhKm7czKB%2bzqI%2fM7a20p1YBh%2fuqIg%3d%3d

6. Verify versions of
        wmenc          9.0.0.2980
        WMEncEng.dll   9.0.0.2980

7. Install Windows Media Encoder Hotfix
        Hotfix for Windows Media Encoder (KB929182)

8. Verify versions of the following files:
        wmenc          9.0.0.3352
        WMEncEng.dll   9.0.0.3352

9. Perform Windows Update to reinstall security updates

10. Verify encoder files remain at current version 9.0.0.3352


Reference:

FIX: You may experience issues when you use Windows Media Encoder 9 Series on a computer that is running Windows Vista
http://support.microsoft.com/kb/929182/en-us