Screwed up my computer via registry

[DigiRev]

Windows XP Professional SP3

I was messing around in the registry which I probably have no business doing.

I went to modify a value for:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_DLLs

To test my program. Instead, I accidentally deleted the AppInit_DLLs key. I re-created it though and made sure I didn't make a typo or something.

Anyway, I restart my computer, and after it is done loading the XP screen with the progress bar, the computer restarts on its own. Last Good Configuration didn't work, safe mode didn't work.

So, I re-installed XP on the same partition (not a good idea, I know) so I can still access my old files. And the registry key being deleted is the only thing I can think of that could have caused it.

Is there some way I can fix the registry on the other installation of XP since I have access to all files on it?

[TheBigB]

Weird. For as far as I know AppInit_DLLs is an optional key; it doesn't have system-carrying function.
But then again... The key not existing could confuse Windows.

As you're almost certain that is the reason I figure something went wrong recreating the value.

The way to load the other registry is to go to regedit, then point selection to HKEY_USERS.
Then goto File -> Load Hive..
The registry hives will be located in [OLDWINDIR]\System32\Config
You'll need the SOFTWARE hive.
Now you can browse the old hive and edit if you need to.

EDIT: Did the new setup backup the old windows directory? If it didn't you can't fix it anymore...

[DigiRev]

Yeah, it's still there as C:\WINDOWS. The new one is C:\WINDOWS.0.

Wouldn't that just load the registry from that installation onto this one? Since I can't log into the other one to do that...

I'm 100% sure I re-created the key correctly with no spelling mistakes. If that's not the problem, then I don't know what is.

[Nightwalker83]

I think (not sure though) that the really important files in the registry would have the option to modify them disabled. It wouldn't make much sense to allow people to access those files so they can cause havoc to a system.

[TheBigB]

What it does is kind of mounting the registry into your own registry, so that you can edit it.

Especially in XP you it takes a mere vbscript programmer to screw up your system, so yes, the easy accessability can cause a lot of havoc.

[Lord Orwell]

I think (not sure though) that the really important files in the registry would have the option to modify them disabled. It wouldn't make much sense to allow people to access those files so they can cause havoc to a system.

you mean like regedit does?

the files in question aren't even being used by his current install. They will be fully accessible.

i suspect one of your drivers used a dll that was no longer registered or something when you deleted that key.

I recommend you import your software key from the old install so your installed programs work, then dump the old xp install.

[schoolbusdriver]

If you have the installation boot CD, you'll have the option to repair an installation - it will probably ask you which one. That should take care of the HKLM problem.

If it works then use "System Restore".

You may also find a backup of your user settings under "Documents and settings/your login name" called "ntuser.dat.rmbak". Check the date first or you may end up wasting your time.

[DigiRev]

Thanks, I'm going to try the repair first before I try to import the other registry stuff...

I'm getting some problems installing programs like Java from having 2 Windows on the same partition.

[DigiRev]

Hm, I popped in the Windows CD and tried to do the Automated System Recovery but I need the floppy and I don't even have a floppy drive.

So I let it get to the screen where it asks which partition that you want to install XP on. I was hoping there would be a "repair" option but I didn't see one.

[TheBigB]

It should pop-up instead of the partition selection...
Have you use the same XP version?
If the system you want to repair is XP Pro, you need to use an XP Pro cd.

[visualAd]

The directory that contains the registry hives also contains backups of the hives:

C:\WINDOWS\system32\config

You need to rename the old hive (which is probably going to be "SYSTEM" in your case) and make a copy of the file "SYSTEM.SAV", then rename that to "SYSTEM". This will need to be done via a command prompt under another installation of Windows.

When you restore the hive, the next time you boot the values stored in the registry will be as they were when the file was first created. This could cause some of your applications to stop working and you may need to re-install / repair them.

[Nightwalker83]

you mean like regedit does?

Yes! Although, from what I remember regedit still gives you the option to edit those important files?

the files in question aren't even being used by his current install. They will be fully accessible.

Yeah, that would make sense since you wouldn't be able to delete it if the system was accessing it.

[Lord Orwell]

Hm, I popped in the Windows CD and tried to do the Automated System Recovery but I need the floppy and I don't even have a floppy drive.

So I let it get to the screen where it asks which partition that you want to install XP on. I was hoping there would be a "repair" option but I didn't see one.

there is a repair option, but you don't actually get to it by choosing repair. You choose new install, and it will tell you "blah blah found a current windows install, what do you want to do?" and asks you if you want to repair it. HOWEVER if memory serves, if you have more than one install on the same partition, it won't let you run it. You can try though.

[DigiRev]

Hm, well I'm going to try that and see what happens.

I wish there was a way I could do a chkdsk on the other installation.

[visualAd]

Chkdisk won't fix the registry.

[Arrow_Raider]

Each time your computer creates a restore point, it creates copies of the registry hives. If using the .SAV backups doesn't fix the problem, you can try getting the backups from a recent restore point. They can be found in
C:\System Volume Information\(GUID)\R(#)\Snapshot

I don't remember the exact path, and I am running Vista which stores restore points slightly differently. But it is something like that above. Higher numbers in the R(#) folders indicate more recent restore points. The date modified attribute lets you see when the restore point was created. You probably won't be able to access the system volume information initially. Google for how to gain access to it.

[schoolbusdriver]

Just one little point - if the boot repair attempt doesn't let you pick the original installation, you may have to modify the path to the correct installation directory in "boot.ini" in the root drive. Probably best done from DOS (not a DOS window) using edit.com.

This may be too late, but if you can alter "boot.ini" and boot to DOS (F8 ??) in the original installation, you may be able to use regedit to export (for examination), correct or even delete the key's value.