Firmware hiccups?

I have been very pleased with my receiver except for a recent problem.
I turned the receiver on 2 days ago and discovered that all my recordings had dissappeared and the usb hard drive was not accessible. The receiver reported that the hard drive was 7% used but I was unable to set recording via the epg. I could not set recordings manually (as per grahamlthompsons instructions). The problem with the manual setting was that I could not set a time earlier than the current time displayed in the setting window. All other boxes could be set as required.
All these problems have dissappeared now and I have reformatted the HDD and have recorded several programmes. As this is a refurbished receiver I am suspicous of its reliability and would want to get back to Humax as quickly as possible if there is a problem. Has anyone experienced these sorts of problems?