Hi,
You can also do the following to resolve this issue.
Restore file and registry security permissions to a known state.
For Windows XP users:
Download and unzip a small utility called Repair Permissions from
http://djlizard.net/software/Repair Permissions.zip
Locate the unzipped folder, and double-click the !RUNME file.
The command prompt window will now open and will begin to restore the file and registry permissions to a known state, please be patient as the command can take some time to complete.
Once the command has completed, try to register a dll file again.
For Windows Vista/Windows 7 users:
Click Start>All Programs>Accessories, then right-click on “Command Prompt” and select “Run as Administrator”
Type in the following command exactly as you see it and press ENTER.
secedit /configure /cfg %windir%\inf\defltbase.inf /db defltbase.sdb /verbose
Wait for the command to complete, it can take some time so please be patient.
Once the command has completed, try to register a dll file again.