One possable cause is you have an enviroment variable set thats causing it
Do a dos session and type SET and look for PATHEXT
Does yours look like this
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH
or does it maybe have
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.INI
If so do u have your original MIRC folder on the path?
