Reboot & Continue, but oops, media has been removed

Hello,

Is there a way to check if the media where [EXENAME] was invoked still exists?

Or perhaps, is there a way to identify the path to [EXENAME] so that I can check if the File-path exists?

It turns out that if one does a reboot and continue and the path to [EXENAME] is not resolvable (E.g. D:\install.exe, where D: is a CD/DVD drive volume and the media has been removed), the reboot portion of the script 'silently' terminates. I'd like to prompt the user to re-insert his/her installation media.

Thx.