OK first of all the identifier to check the validity of mirc.exe is $md5($mircexe, 2) - without the 2 for the second parameter it's calculating a digest of the filename as a peice of text instead of for the file it's pointing to. For the file it should return e72425de3cb77a4ddff9289f728017b4.
Assuming that isn't the problem you need to make sure there aren't any scripts still loaded. I know you said you removed sysreset but I wouldn't count on a script unloading itself correctly. To see if you have any scripts loaded open up the Scripts Editor and go to the Remotes tab. From there you can unload all scripts from the menubar. Restart mIRC (this is important!), and then see if mIRC still crashes.
If the problem still isn't fixed you might want to run a virus scan to make sure that isn't the problem. If the issue is still occurring try temporarily disabling your Anti-Virus software and see if that fixes it.
