Can not block more degrading

Hello
Have a problem and indeed can not, after some time his blocks more degrading.
But can the blocks which were built before we even degrading. There are all on the server where the matter is on the map. After server restart everything goes back to normal until a certain time then the game laggy and the problem is back.

- bukkit 440 MC 1.3 (with or without plug-ins the same problem)

Please help.








2011-02-28 11:08:43 [INFO] Starting minecraft server version Beta 1.3
2011-02-28 11:08:43 [INFO] Loading properties
2011-02-28 11:08:43 [INFO] Starting Minecraft server on 192.168.1.26:25565
2011-02-28 11:08:43 [WARNING] **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!
2011-02-28 11:08:43 [WARNING] The server will make no attempt to authenticate us
ernames. Beware.
2011-02-28 11:08:43 [WARNING] While this makes the game possible to play without
internet access, it also opens up the ability for hackers to connect with any u
sername they choose.
2011-02-28 11:08:43 [WARNING] To change this, set "online-mode" to "true" in the
server.settings file.
2011-02-28 11:08:43 [INFO] This server is running Craftbukkit version git-Bukkit
-0.0.0-458-g557f3d2-b440jnks (MC: 1.3)
2011-02-28 11:08:43 [INFO] Preparing level "Wold"
2011-02-28 11:08:43 [INFO] Preparing start region
2011-02-28 11:08:44 [INFO] Done (959568604ns)! For help, type "help" or "?"

 

Sorry I don't understand the meaning of degrading here.