This morning my X1000 wouldn't start when I pressed the on/off button. After I unplugged the X1000 and pugged it back in several minutes later it started when I pressed the button. Then I noticed the time was no longer correct. I tried to turn the system off but it would not shut down. I searched these forums and found a 3 year old post about the same problem that was solved with a new battery. I replaced my clock battery and the problem was solved; didn't lose my CFE settings either. I checked the voltage of the old battery and it was 1.48 volts. It's a wonder my system worked for as long as it did.
My system is 3 years 3 months old, so it looks like the battery life for an X1000 is approximately 3 years. If you've had your X1000 for 3 years or more, it might be wise to replace your battery before mysterious problems occur.