Fist the bad news: No, Firefly isn't coming back. But, if you've ever felt like the ratings system didn't accurately represent the popularity of your favorite show, this might be something to take note of. Today The Nielsen Company issued a statement admitting it found a "technical error that impacts national network television ratings over several months." The problem apparently didn't apply to cable networks or local TV, but given their impact on billions of dollars in advertising, even a small problem can be significant. According to reports ABC benefited from the glitch, which became more noticeable as the fall premieres rolled out. For several days in a row, the network's TV shows always gained ratings between early morning quick estimates, and later more complete reports. The error started on March 2nd, but Nielsen says it will reprocess data going back to August 18th, when the first network fall premiere aired -- maybe next time they'll stick to just counting Tweets.