cmdlineext02.dll

A while ago I kept finding a DLL in my temporary directory, an odd place to store a DLL, and mentioned it in my LiveJournal in a post titled I have a strange thing. So far that's proven to be the most popular post there in terms of comments, simply because there isn't a lot of information about the DLL on the web.

The library appears to be installed with a number of games. I got it most recently from Rollercoaster Tycoon 2. It may be created by other games, and may well be something to do with copy protection which requires you to keep the CDROM in the drive while you play. One person thought it might be preventing the copying of games altogether. CmdLineExt03.dll is likely to be a variant of 02, though so far no one has reported a CmdLineExt01.dll. The file is recreated on bootup if it's deleted.

Other games which may install it include Unreal Tournament 2003 (possibly only before the patch which removes the need to keep the CD in while playing), Grand Theft Auto Vice City, Nascar Racing 2003, Diablo 2, and quite probably some non-game software.

The latest anonymous comment suggests creating a directory with the same name as the file in order to prevent it coming back. Cunning!