Unable to install 10.1C04 Service Pack on Windows XP machine

SYMPTOM(s):

Unable to install 10.1C04 Service Pack on Windows XP machine.

Installation of 10.1C service pack 04 fails with:

OpenEdge r10.1C installation corrupted:
"DLC" registry key not found.
Click OK to exit.

FACT(s) (Environment):

Registry Keys in HKEY_CURRENT_USER\Software\PSC\PROGRESS are correct.
PROENV window is able to locate the DLC environment variable.
Can connect to database via SQL without getting any errors.
Windows XP
OpenEdge 10.1C

CAUSE:

The DLC and PROPATH string values are missing from HKEY_LOCAL_MACHINE\SOFTWARE\PSC\PROGRESS\Startup.

FIX:

1. Use regedit to go to: HKEY_LOCAL_MACHINE\SOFTWARE\PSC\PROGRESS\Startup .
2. With the mouse on the Startup press right mouse key and select New -> String Value.
3. Create a String value and call it DLC.
4. Then set the Value name: DLC and the Value data: (should be the path of your OpenEdge installation).

Example:
Value name: DLC
Value data: C:\Progress\OpenEdge
5. Exit regedit.
6. Run setup.exe again to install the Service Pack you were experiencing problems with earlier.