>Hello.
>RegDeleteKey allways return 5. Can anybody explain what is the error.. and maybe where can I find error description in future..

Access is denied. You do not have the necessary permissions. Under NT or Win2K, it may also indicate that you're trying to delete a registry key that has subkeys; NT/2K only permit you to delete a key that has no subkeys. Recursive deletion would require using SHDeleteKey().

You can use ErrLook.EXE which ships as one of the Common Tools with Visual Studio to display the meaning of standard Win32 errors. You can use the FormatMessage() API call to retrieve a generic text description of an error code returned through the API. You can try looking at the MSDN Library entry for RegDeleteKey() which explains possible problems.