I had a pair of HR24-500s installed a week or two ago, along with a few other receivers. Both of the HR24s were having problems - they would lock up, the screen would freeze and then a few seconds later they would reboot themselves. A tech came out today to replace them, he said that there was a "bad batch" from HR24-500s, he had replaced 3 others earlier today. Has anybody heard of anything like this? He replaced one with an HR24-100 and the other with a -200. As far as I can tell there's no difference between them and the -500, I've read that the only difference is the manufacturer. Is that correct?