RoK is a game still in testing, and DM has no official backing or funding to support its development. As a result, the game is literally run out of his home, with his own equipment, and updated on his own time. The current server equipment is old and overtaxed, and as a result issues like lag and crashes are common.
In the past crashes happened sometimes every few minutes, and losing items, gold and experience were commonplace. DM has implimented fail-safes that backup data regularly help prevent that now, but crashes still happen.
When the server crashes, it can do a couple things...either it can automatically restart and be back up within mintues, or it can have some kind of error or fatal problem that must be dealt with before it can come back online. If that's the case, it can sometimes be hours before DM can get back to it and get it online.
Also keep in mind, the server automatically restarts at midnight and six AM Eastern time for daily maintence and to keep the system running smoothly. These resets can last from 5 to 20 minutes at a time.
When the server is down, it's a good time to get up and do something else, get away from the computer and spend a few minutes in the real world. If you just can't pry yourself away from your keyboard, Cerixus has listed some really entertaining time-wasters on his site, www.Cerixus.com. Also, DM's band website - www.DowntotheShake.com, has some really neat stuff in it's arcade.