Synchronization and syntonization...

Synchronization and syntonization...  It's amazingly difficult for a computer to keep very precise time.  Anything more accurate than within a second or two of accepted standards is a major challenge. 

I first ran into this when working for an electronic trading company, where we were required (by regulatory agencies) to keep our logs accurate to sub-second levels.  When I was given responsibility for the IT organization, one of the first things the team hit me with was that we were out of compliance with the regulations.  In fact, our servers weren't even able to stay with 10 seconds of the “correct” time!  Fixing that problem took months of very hard work by several people on the team, mainly to make sure we had no delays (from network gear, mostly) between our logging servers and their time source. We also had to buy $20,000 worth of special “Stratum 1” NTP servers that were synced to atomic clocks on GPS satellites. 

It's gotten a little cheaper these days, but not really any easier...