The F5 does not stop to break to cause the server of FreeBSD paralyze the problem

[abbish]

Managing person good:
My system is a FreeBSD+ Apache+ PHP4.10+Mysql4.08 do the WEB server usage, appearing to open a Web page to press down the F5 now not to stop to break, would appear the CPU to take up the rate 100% memory  usage quantity to explode the full circumstance, please ask how to solve?
I am Chinese, my English is not so good please forgive, this problem seems the common problem that all usages FreeBSD installs the WEB server, pleasing the conferrable reply, thank!