I have to manage a site which wasn't developed by me. It is in PHP using a mysql database, which is located in the web server. The site, sometimes (when the visitors increase too much) stops responding, or respond too slow.

I have developed some sites in PHP but never took care of the management so really don't know where to start. The server (the hard) seems to be fine, when the web stops responding the cpu is being used at about 55% and has a lot of memory.

I'm not asking someone to solve this issue. I only would really like if someone could give me a few tips about where can I find logs and how should I read and interpret them. So, that way I would be able to know if its the net traffic, the database (which queries), or what.

Thanks!

Update: Forgot to say: it is a Windows Server 2003.

Note: I've recorded about a day with Jet Profiler. I don't really understand all the information it provides but there is one query which it marks as really slow. It makes sense because it is a select with a where clause which has three like condition. Initially I didn't include this in my question because when I run the query from MySQL Query Browser it doesn't take any long. It is under 0.01 seconds.