after starting the server after a few minutes, zabbix_server dies:

44644:20100617:200155.242 file:dbcache.c,line:2576 zbx_mem_malloc: out of memory (requested 48 bytes).
44556:20100617:200155.243 One child process died (PID:44644,exitcode/signal:65280). Exiting ...
44572:20100617:200155.244 Got signal [signal:15(SIGTERM),sender_pid:0,sender_uid:0,reason:0]. Exiting ...
....
44634:20100617:200155.265 Got signal [signal:15(SIGTERM),sender_pid:0,sender_uid:0,reason:0]. Exiting ...
44556:20100617:200157.266 Syncing history data...
44556:20100617:200202.893 file:dbcache.c,line:2576 zbx_mem_malloc: out of memory (requested 24 bytes).

47205:20100617:201626.997 file:dbcache.c,line:2576 zbx_mem_malloc: out of memory (requested 48 bytes).
47098:20100617:201626.998 One child process died (PID:47205,exitcode/signal:65280). Exiting ...
47132:20100617:201626.999 Got signal [signal:15(SIGTERM),sender_pid:0,sender_uid:0,reason:0]. Exiting ...
......
47201:20100617:201627.045 Got signal [signal:15(SIGTERM),sender_pid:0,sender_uid:0,reason:0]. Exiting ...
47098:20100617:201629.060 Syncing history data...
47098:20100617:201629.261 Syncing history data... done.
47098:20100617:201629.261 Syncing trends data...
47098:20100617:201642.946 Syncing trends data... done.
47098:20100617:201642.946 Zabbix Server stopped. Zabbix 1.8.3 (revision 12779).

increase in the parameter CacheSize from 128M to 256 or 512 - no effect
server has about 50k active items