Strange Server Problems

[Kevin]

Hi All,

I have a dedicated server running FreeBSD 7.0 release, it has been running
well for two months. Suddenly, some websites stopped responding, all
websites hosted on this server are simple PHP sites, if one site is working,
all of them should work. I checked the bind/apache/mysql, everything is fine
(otherwise no websiets would be working). Could anyone please give me some
hints? Where should I start to look into this problem?

Thanks,

Kevin