救命啊java.lang.OutOfMemoryError: unable to create new native thread

运行环境：win2003+jdk1.5+tomcat5.5
java虚拟机配置内存1300M

报错信息如下
2006-9-27 14:57:56 org.apache.tomcat.util.threads.ThreadPool$ControlRunnable run
严重: Caught exception (java.lang.OutOfMemoryError: unable to create new native thread) executing org.apache.tomcat.util.net.LeaderFollowerWorkerThread@a191a8, terminating thread
一天要重启几次

同时k状态的线程特别多
到底是什么原因
请高手帮我看看怎么会事啊