I have an Apache web server v1.3.19 on Windows 2000 with PHP v4.0.5.
I have the following problem:

During the whole day until hour 22:00 the web server works acceptable. I mean it really works, faster or slower but it works. I've noticed that the php session directory has an average of maximum 1000 session files in this time.
After 22:00 my web server becomes very loaded because of our dial-up users which have the habit (the phone tax is cheeper in the nightime in Romania) to enter at this hour. Then the php session directory reaches very easy an average of 3000 session files and then the web server nearly dies. If I reset the web server it works for 5 minutes and then it dies again. After the hour 24:00 when the users go to sleep the web server works fine again and the php directory has an average of 600-700 session files.
Does it seem a problem or am I crazy ?

P.S. The problem is reproduceable with IIS v5.0 and PHP v4.0.5 too. 

Thank your for your opinion whatever it is.