A PC got incrediby low on disk space. After restarting, all settings were lost so no desktop wallpaer, can't save one, can't customize the Start Menu using START |PROPERTIES. MS Office won't run. Registry looks OK in visual examination.
Ran sfc and it is OK.
When installing a program, I get Error Creasting Registry Key, Access Is Denied. RegCreateKeyEx failed: code 5
Any advice other than a complete XP reinstall?