Registry Cleaner XP critical error

Hi,
I have downloaded Registry Cleaner for my Windows XP but when I attempted to scan & Fix Registry an error message displayed during the cleaning process. How can I avoid these errors?
I really need your assistance to fix this immediately.
Any help would be appreciated.
Thanks in advance.

RegistryCleanerXP found 43 critical errors on your PC>
Click the "Fix Error" button to repair these errors.
