File association not working properly.
Had a PC with XP installed on D with the programs.
Needed to wipe PC so took backup of users profile.
Wiped and reloaded XP to be on C. After user logged in once, copied old profile back over.
Trying to associate a .asc file to open in excel refused to work. Open With would allow you to browse to where office was installed, select Excel OK but it then still wouldn’t appear in list.
Turns out this is due to copying the profile over from the old setup. That profile still sees some programs as being installed on D and sticks these entries in the registry, despite D no longer existing.
You can go to (in this example its Excel):
HKEY_CLASSES_ROOT\Applications\Excel\shell\open\command
When I got there, sure enough, it was pointing to the D drive for the Excel install. Changed this to C and fixed the issue.
Archaeous post on this thread helped:
http://social.technet.microsoft.com/Forums/en/w7itproui/thread/3ddd2350-6323-4f3c-9377-dba0acb53a33
This program may also be useful