See my posting in the WinAMP Technical Support forum from earlier today entitled "Midi file NOT ending in WinAmp but fine in other programs"
which has an explaination for the posting AND serveral files that demonstrate the problem in various forms. The FIRST posting has the main example, where I cannot find the problem in the file. Play it in WinAMP with the latest version of the midi dll and you will see it is NOT ending at the right time, but goes for hours! Play it in almost any other player and it takes about 3 and a half minutes. The problem is most likely in the DLL but it happened in the unpatched one which would not play some midi files and still happens in the latest, patched, version, so it may be elsewhere. In any case, it is a problem and most likely is a bug in the dll.
The files are in the other forum so I will not repost them here.