[error] server reached MaxClients setting, consider raising the MaxClients setting

Hi all,

I have a problem with my Server version: Apache/2.0.54. I am getting
the error: [error] server reached MaxClients setting, consider raising
the MaxClients setting, but if I have a look through the access_logs
at that time, there is max one attempt, but the server seems to be
down over minutes.

My settings are:
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxClients 256
MaxRequestsPerChild 1000

4 CPUs:

model name : Intel(R) Xeon(TM) CPU 3.20GHz

RAM:

MemTotal: 5192728 kB

and before and after that time when the error occurs there are not
many clients that are trying to access the server.

Is that a bug? Or are my settings wrong?

Thanks.

Cheers Marcus