Hello,
I have been monitoring your vps for some time. At one time the number of connections on port 80 reached to high value which I guess the main reason behind failure of httpd process.
Following changes have been made now in httpd.conf to improve the webserver performance :
Persistent connection has been enabled by changing value of
KeepAlive to
On and Increased the value of
ServerLimit
Apart from this, resolvers of the vps has been changed just to improve the performance of your vps as well as the sites.
Please feel free to update the ticket if you need further assistance.
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Regards,
AlanV 
VPS Support Team
UK Web Hosting, Website Hosting, Web Hosting UK, Web Hosting