Please when posting for help make sure that ALL spelling is correct.
The correct file name is Sulfnbk.exe,
Sulfnbk.exe, is a Microsoft Windows 95/98*Grinler utility that is used to restore long file names, and like any .exe file, it can be infected by a virus that targets .exe files.
The Sulfnbk.exe file is not required to run Windows. It may be necessary if you need to restore long file names if the file names become corrupted. For additional information, read the Microsoft Knowledge Base article Description of Sulfnbk.exe and How to Replace the Program File (Q301316)
Let us know if this solves your issue.
Thank you Jitaa