Ok, using Windows 7 Professional, have upgraded my Two-Up printer to the 3up by DDegonge888 on Thingiverse. With Rep-Host 1.5.6, I had no issues. I have the red Printrboard Rev. D. Was printing fine from the SD card as always, then upgraded to Repetier Host 1.6.1. I was able to see what was on the SD card when it was in the Printrboard. I was unable to print anything that was on that list. Was unable to load anything to the card through Repetier Host, but after I tried, and then took the card out and used a dongle, I would see some sort of file that tried to be loaded onto the SD. Basically the only function was the ability to read what was on the card, no write or run options worked. Uninstalled 1.6.1 and then reloaded 1.5.6 and was able to run again. Also not sure if it's related, but when you hit print from SD, you can't disconnect while the Hot end is heating up, locks the program up and the hot end keeps heating.