In addition to what PABear posted, you can edit the Permissions on this
registry key to see if doing so will allow the installation of SP2 to
Start > Run > type in
Click OK or press Enter
Click the plus sign next to HKEY_CLASSES_ROOT
Scroll down to .dvr-ms
*Right* clickt .dvr-ms and choose Permissions
Make sure that System is listed with these Permissions:
If not, check those boxes and then click Apply, OK.
Close the registry editor.
Then read the pre-installation links that PABear provided.
IF the Access Denied message appears after doing all of the above, check
specifically, the 'Access Denied' section.
MowGreen [MVP 2003-2008]
> I'm trying to install Windows XP service pack 2 to no avail. During
> installation process, I received the following error message,,,"Service Pack
> 2 Setup could not backup registry key HKCR\.DVR-MS to file
> C:\\WINDOWS\$NtServicePackInstall$\reg00013. 5:Access is denied.
> Would anyone know what this is and how this could be resolved? Thanks