vps - Multiple instances of HTTPD running, and virtual memory constantly running out?

I've noticed my VPS behaving weird today. I have set it up as a web server (along with MySQL, PHP, FTP etc) and at the moment there is only one website running on there. I noticed earlier today that the website would loose connection to the database intermittently, and would also fail to load at all.

I opened Webmin and when it eventually loaded (it took a while) it reported back that the CPU usuage for I/O was 100%, and that 125.39MB of the 125.47MB Virtual RAM was used up. I reset the VPS and after it came back online, the CPU read that it was running at 100% Idle and that 0KB of RAM was being used.

After 1 hour 44 minutes, the server now says that I'm using 7.36MB of RAM. It also says that I have 66 processes running, and on looking at that I have 9 instances of httpd service running.

I'm thinking that the httpd services are eating up the RAM and CPU (each instance is reporting that it's using roughly 330000KB of RAM). As I only have one website running on the server (and one instance of Webmin) shouldn't I expect to see only one instance of httpd running? Or is this normal?

If the multiple instances of httpd aren't the problem, what else could be causing these issues?

EDIT:
The processes listed by CPU usage are:

ID      Owner       CPU     Command   
2401    root    1.3 %   /usr/libexec/webmin/proc/index_cpu.cgi
1   root    0.0 %   /sbin/init
2   root    0.0 %   [kthreadd]
3   root    0.0 %   [migration/0]
4   root    0.0 %   [ksoftirqd/0]
5   root    0.0 %   [watchdog/0]
6   root    0.0 %   [events/0]
7   root    0.0 %   [cpuset]
8   root    0.0 %   [khelper]

9   root    0.0 %   [netns]
10  root    0.0 %   [async/mgr]

The processes by RAM are:
1034    mysql   444648 kB   /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --log-e ...
1156    apache  334512 kB   /usr/sbin/httpd
1157    apache  333728 kB   /usr/sbin/httpd
1161    apache  333728 kB   /usr/sbin/httpd
1136    root    319352 kB   /usr/sbin/httpd
1158    apache  319352 kB   /usr/sbin/httpd

1159    apache  319352 kB   /usr/sbin/httpd
1160    apache  319352 kB   /usr/sbin/httpd
1162    apache  319352 kB   /usr/sbin/httpd
1163    apache  319352 kB   /usr/sbin/httpd
882 root    248576 kB   /sbin/rsyslogd -c 4
1144    root    117072 kB   crond
1960    root    108212 kB   -bash
945 root    108076 kB   /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/my ...
1957    root    97456 kB    sshd: root@pts/0
2486    root    67068 kB    /usr/libexec/webmin/proc/index_size.cgi

1164    root    64152 kB    /usr/bin/perl /usr/libexec/webmin/miniserv.pl /etc/webmin/miniserv.conf
2489    root    64152 kB    /usr/bin/perl /usr/libexec/webmin/miniserv.pl /etc/webmin/miniserv.conf
909 root    63756 kB    /usr/sbin/sshd
1135    postfix 62220 kB    qmgr -l -t fifo -u
2062    postfix 62048 kB    pickup -l -t fifo -u
1126    root    61968 kB    /usr/libexec/postfix/master
1   root    19112 kB    /sbin/init
2498    root    11208 kB    sh -c ps --cols 2048 -eo user:80,ruser:80,group:80,rgroup:80,pid,ppid,pgid,pcpu, ...
2499    root    11092 kB    ps --cols 2048 -eo user:80,ruser:80,group:80,rgroup:80,pid,ppid,pgid,pcpu,vsz,ni ...
358 root    10860 kB    /sbin/udevd -d

615 root    10856 kB    /sbin/udevd -d
894 root    3988 kB /usr/sbin/acpid
1172    root    3984 kB /sbin/agetty /dev/ttyS0 9600 vt100-nav

Answer

I tracked down the problem to Webmin running. I've left the Webmin service off all night and the RAM usage is under control now. I have now since deleted Webmin and using ISP Config 3 instead. Again, the RAM usage is incredibly good now.