If you're getting the CHK error when launching DP 2.6, download the updater to DP 2.61MTS which should fix this problem. (motu.com follow the downloads link to the DP link) The DP 2.61 updater will only update Digital Performer 2.6. If you're using an earlier verison of DP, please contact Tech support with your full name, address and Digital Performer serial number. (techsupport@motu.com)