Sorry to hear your Iscan is the problem. I upgraded from the V1 of the Iscan to a CI. The system worked fine except I had to install a RGBVH card that allowed me to terminate one side. Don't ask me why this was a problem, but my original dual input card had a sync problem only with the CI. It worked(s) fine with the DVDO, Sony HD100, and a computer. After resolving the problem with the input card, I have had no problems with the CI and 4100. Even my ISF tech who did the calibration was impressed with this setup.
---Andy Garabedian