A program that can secretly change your dialup connection setting so that instead of calling your local internet provider, your PC calls are routed to an expensive 0900 or international phone number.
Dialers are software that dials a phone number. This usually happens without the end user knowing about it - causing long distance charges.
Open a DOS command prompt window (from Start->Programs->Accessories) and enter the following commands:
regsvr32 /u ngd.dll
Next, open the registry (Start->Run->regedit) and find the key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run. There is likely to be an entry pointing to a porn dialler in the root folder of the C: drive, for example C:\xxxvideo.exe. If so, delete this value.
Restart the computer and you should be able to delete the 'ngd.dll' file in the System folder (in the Windows folder, called 'System' on Windows 95/98/Me or 'System32' on Windows NT/2000/XP). You can also delete dialler files in the C:\ root folder, such as xxxvideo.exe, hotporn.exe and possibly others with similar names, along with 'dp0.dll' if you have it.