Re-register Windows XP Components or Use In-Place Windows Reinstallation
If the problem is with one component or two, or you wish to add some components, it is recommended that you use the built in Windows Component Management feature in the Control Panel. You may also use the command "Regsvr32" that helps you re-register the components you want.
However, if you wish to re-register all the components, it is easier to go for an in-place install of Windows XP as it will take too much research to locate the "dll library" for each Windows XP component and then register each "related dll file" using the command. Re-registering all the Windows XP components is required when: Windows XP fails to behave properly due to registry problems, file associations and permissions go corrupt resulting in unstable working conditions, or the system files are damaged or missing.
Using the RegSvr Command: If you know the "dll files" related to the Windows XP component, which you wish to register, you may use the "RegSvr" Command from the command line (Start Menu ---> Run). The usage of RegSvr command is as follows:
An example to fix the Windows XP component for display problems could be registering disp.dll. Under the case, you will be typing "RegSvr C:\windows\system32\disp.dll". You may check out similar usage of RegSvr by visiting this page.
If you are not comfortable using the command line, you can check out the feature to manage Windows Components (through Control Panel) to add and re-register Windows XP Components. The next page explains this process.