Apache acts like has reached to the maximum client but it is not

Apache acts like has reached to the maximum client value and I can't see even default apache's "works" page but it is not. I can see that from server-status. It is also a development server and restricted with intranet. So, not possible.

I also re-defined ServerLimit and reduced timeout value, turned off keepalive in Apache's config but nothing change. What would you suggest ?

A few extra info :

It is a virtual machine ( VmWare )

Ram amount : 512 Mb / Actual usage ~150mb

CPU : 1 x 2.40 ghz / Load : 0.00-0.050

Apache version is 2.2

Solution

check the logs
Apache creates one new child process per second, only one. Try to increase StartServers and MinSpareServers. If you know how many apache child you can put in your memory put that number for MinSpareServers, MaxSpareServers, StartServers and MaxClients
512M is short. If one Apache process takes 64M (usually it's around 20MB, but with things like Drupal we sometimes see 128M per process), then you can only handle 512/64=8 child process, so a MaxClient=8. If you tell Apache that the MaxClient is 150, then give it some RAM to handle that, or check that your application is not eating too much RAM.