php can't work under heavy load?!

I sucessfully install php4 for netscape www server, But when I use it as chat server,if the login people upto 300 or so,then others can't login into chatroom. view the acess log of the www server,it seems that the server auto reset: [27/Jul/2000:17:04:53] verbose ( 3679): successful server startup [27/Jul/2000:17:04:53] verbose ( 3679): Netscape-Enterprise/3.6 SP3 B99.280. 0054 [27/Jul/2000:17:04:53] info ( 3679): php4_init reports: Initialized PHP Module [27/Jul/2000:17:04:53] verbose ( 3679): dstats: Using slotbase = 0 start = 0 end = 10240 last = 0 slots pid = 3679 [27/Jul/2000:17:04:55] warning ( 3679): for host 63.210.112.33 trying to GET /face/49.gif, start-http-response reports: write failed (Broken pipe) [27/Jul/2000:17:04:56] verbose ( 3681): successful server startup [27/Jul/2000:17:04:56] verbose ( 3681): Netscape-Enterprise/3.6 SP3 B99.280.0054 [27/Jul/2000:17:04:56] info ( 3681): php4_init reports: Initialized PHP Module ---------------------------------------------- any idea? When the problem appears,The pages use php can't work,but pure html work fine. os :Solaris2.6 web server :Netscape Enterprise 3.62