Nopir.A is a worm that deletes all the files with a COM or MP3 extension from the affected computer. Therefore, on Windows 2003/XP/2000/NT computers, the file NTDETECT.COM will be deleted, and the computer will not start.
This worm modifies several computer settings, as it disables the Task Manager, the Windows Registry Editor and the Windows Control Panel.
Nopir.A also modifies certain entries in the Windows Registry, in order to be run whenever the user runs an EXE, COM, PIF, SCR, CMD, BAT, REG, VBE or VBS file. Additionally, if Nopir.A is deleted without taking any precautions, the user will not be able to run files with those extensions.
Nopir.A spreads through the peer-to-peer (P2P) file sharing program eMule.