Repair Windows XP and then Restore

[LykanthricAura]

Ok. I have Windows XP and its like my alternative OS thing for playing old games. I installed something that required a restart and its making my XP crash during boot. Its boot, gets through the loading, but before login screen the system restarts.

I was thinking of using a CD to "Repair" the installation. But I dont want to lose the Registry and have to reinstall all the program. The XP partition doesn't have any data except programs and the Registry.

Is there a way to---

1) Repair and then Restore the Registry? As it was....
2) Make everything normal.

I mean I know I can backup the Documents and Setting folder ...the Application Data etc to retain my browser history, bookmarks, application settings...etc. But what about the deeper stuck? Windows Registry, installations (not the data in the Program Files folder, the actual installations... Stuff you can see in the "Installed Programs" in Control Panel) ..etc

I was thinking of Backing Up everything. And then Putting it back in after installation. Will that work? If I basically backup all the Registry files... NTUSER data, etc. But I dont know how to backup the "Installed Programs" thing.

[Geek-9pm]

Can you boot in safe mode?
Have you ever done the XP repair option? Often it works very well and makes only minor changes to the system. It depends on how much damage.
My first choice with any XP problem is to boot in safe mode and do the SFC option.
https://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/system_file_checker.mspx?mfr=true
SFC inspects important system files and  replaces them if needed. Of course, you need to have the CD in the drive.
At the command line, the command is:
SFC /scannow
Try it. 

[patio]

What did you install ? ?

[LykanthricAura]

Pinnable Game Profiler.