registry_error xp pro sp 2

[georg]

I have XP Pro SP2 running on a 933 P3 with 512MB RAM. It is a used machine that used to be part of a domain in a medical office. No CD. Originally was Win98 system and drive is formatted FAT32. App software installs and runs well, but there are problems with the operating system itself which I would like to understand, and fix if posssible.

Restore points are saved but the user interface in system tools does not run, so cannot restore.

SFC does not run and no CD or files to check against, except DLL cache.

System information does not run, but apps like Belarc or PC Wizard run fine.

The XP Defrag does not run. Says "cannot create a required resource". Auslogics runs and completes OK.

Any attempt to export the registry produces a system halt due to "registry_error". Same result if registry is searched.

The help system services run but help will not run.

MS Office XP 10.0 uninstaller would not complete. There are artifacts that still try to load after a brute force removal.

I foolishly removed the machine from the domain and can't seem to rejoin it, or log on to the former user accounts. Registry cleaners complete OK, except for the Eusing cleaner which bombs if HKEY_LOCAL_MACHINE is checked.

No passwords and I log on as Administrator. Also tried logging on as Administrator in Safe Mode. Regedit runs and I can manually edit the registry. I have tried enabling all services, and also have tried copying the services config from an XP Home Edition machine where everything works. I uninstalled all updates hoping key files might be restored.

This is not my primary machine. It is used to try out freeware and tweaking suggestions and runs well enough for that purpose, but ignorance and lack of control over the machine irritate me.

Suggestions and/or comments will be appreciated.

[georg]

Update: system restore now fixed. pchshell.dll was missing from the PC Health binaries folder.

[georg]

Update2: Defrag is fixed. Copied missing registry key from XP Home Edition system.

My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Dfrg