OK I don't know where you got your mIRC installer from or if you've run any "patches" for the mirc.exe but that's not a valid MD5 digest for 6.21, 6.3, or 6.31.
The correct digests (values returned by $md5($mircexe, 2)) are:
6.31: e72425de3cb77a4ddff9289f728017b4
6.3: 283e22b5311637773c0263033334cfdd
6.21: 52f9f2101923e84dd146fd1058d97b60
This is almost certainly the source of your problem.
