Press Menu-6-3, then Info-right-left-TV/AV, confirm corruption with Select. Escape out with LiveTV. Press and hold Power button on receiver until it reboots. This will reset all counters and some user settings. You also have to rescan OTA stations if applicable. You will have to redo the Guide view and CC setup, as well as output resolution. You need to redo the recordings layout with what groups the recordings go to. But the groups will not be deleted. It will not delete timers, and not the check switch. This is actually an NVRAM reset. I do this all the time, as my 722 reboots often without warning.