grind to a halt

2012-02-12 00:33:43 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:33:43 [INFO] [WorldBorder] [Fill] 305 more map chunks processed (58361 total, 0.4%) (free mem: 463 MB)
2012-02-12 00:33:45 [INFO] Chest has records in it!
2012-02-12 00:33:46 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:33:48 [INFO] Chest has records in it!
2012-02-12 00:33:48 [INFO] [WorldBorder] [Fill] 276 more map chunks processed (58637 total, 0.4%) (free mem: 269 MB)
2012-02-12 00:33:48 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:33:49 [INFO] Chest has records in it!
2012-02-12 00:33:49 [INFO] Chest has records in it!
2012-02-12 00:33:52 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:10 [INFO] [WorldBorder] [Fill] 252 more map chunks processed (58889 total, 0.4%) (free mem: 961 MB)
2012-02-12 00:34:10 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:15 [INFO] [WorldBorder] [Fill] 380 more map chunks processed (59269 total, 0.4%) (free mem: 763 MB)
2012-02-12 00:34:17 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:20 [INFO] [WorldBorder] [Fill] 240 more map chunks processed (59509 total, 0.4%) (free mem: 591 MB)
2012-02-12 00:34:20 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:22 [INFO] Chest has records in it!
2012-02-12 00:34:23 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:25 [INFO] [WorldBorder] [Fill] 257 more map chunks processed (59766 total, 0.4%) (free mem: 569 MB)
2012-02-12 00:34:25 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:30 [INFO] [WorldBorder] [Fill] 403 more map chunks processed (60169 total, 0.4%) (free mem: 368 MB)
2012-02-12 00:34:32 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:34 [INFO] Chest has records in it!
2012-02-12 00:34:35 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2012-02-12 00:34:35 [INFO] Chest has records in it!
2012-02-12 00:34:35 [INFO] [WorldBorder] [Fill] 272 more map chunks processed (60441 total, 0.4%) (free mem: 186 MB)
2012-02-12 00:34:35 [INFO] [WorldBorder] [Fill] Available memory is very low, task is pausing. Will automatically continue if/when sufficient memory is freed up.
 Alternately, if you restart the server, this task will automatically continue once the server is back up.