As many of you have noticed, the system was unavailable today from early afternoon until about 9:30PM tonight. I wish that I could tell you just exactly what was hosed, but the system was hung when I got to it and the log files did not provide any useful information whatsoever. The only possible cause that I could imagine was that the box went thermal since the air filter was completely clogged. Then again, it didn't get that hot today.
That being said, I just power-cycled the box and it appears to be functioning normally once again.