If you face any missing files or unregistered file, usually from dll and ocx file when your running yahoo tools or any yahoo applications program in your windows Vista, you may need to register the dll or ocx files first before you install it.
To help you to register those files, you can use Vista DLL OCX Register Software. Remember usually the dll file placed in you window system32. List of dll / ocx file that might need to register: fussionbutton.ocx, mswinsck.ocx, acskin4.ocx, YMSG12ENCRYPT.dll, comdlg32.ocx, Kewlbuttonz.ocx.
Download Vista Register ocx
You can download the register ocx file at the links below: