C:\Program Files\Internet Explorer\iexplore.exe
My iexplore.exe isnt on the c drive. as it was mentioned. Just use /run iexplore.exe
There are programs that do not require a full path to the exe. Outlook.exe is one. Probably only MS programs, I dunno. Play around with em.
I scan the drivers from C: to F:, then locate the exe files i want to set a path to, if they arent found mirc will ask the user to browse for it, so if a user have a diffrent path is no problem