I'm also experiencing the same problem with the program guide not updating. I get the mc2xml v1.4 dialog box, which keeps bringing up the "OK" box to click. When I do, the whole mc2xml guide process loops and I get the "OK" box to manually click on again and again. Finally, it goes on in the process to the "mc2xml - lineup selection" and gives 2 choices for Los Angeles OTA Antenna (6 and 7). If I choose either, it goes back to the previous process with the mc2xml v1.4 dialog box and the "OK" box again! After that, I get the terse message, "The guide data is not valid, or does not contain any program information" and an OK box to click to exit the routine. Before this daylight savings or whatever external event is causing the problem, everything was working automatically.
Update: as of 3/16/2016, mc2xml is working again for Los Angeles OTA Antenna option 6. I'm glad this issue has been resolved.