Gary has recently posted a new build of MARK (build date Mar-7-2004). If you have an older version of MARK, you're urged to upgrade. You can grab the installer from either Garys MARK page, or here:
http://www.phidot.org/software/mark/download/
As always, the preferred upgrade path is to
1) uninstall your current version of MARK
2) download and install the newest version