If you use a Linux-based server for the DC forum, you might already have taken a look at one or more misbehaving processes with a tool called:
htop. Use a terminal multiplexer (
Terminator is one of those). Those allow you to divide up your terminal screen into different sections and in each section you can start a new session. This makes working with the command-line a lot more efficient. Once you have used a multiplexer in there, you won't go back.
A misbehaving process might already give you an indication where to look. You are likely to use a Windows system to log into your server, so it could be a good idea to use a better solution than Putty. That is called
SmarTTY.
If you use a Windows-based server for the forum, you might take a look at:
TaskExplorer which happens to be featured on ghacks.com today. With that tool you can see more info regarding any process than you can with Process Explorer from SysInternals. While process Explorer is executable with a size of about 2.5 Mbyte, extracting the Task Explorer results in a whopping 60 MByte, which happens to be bigger that the whole
SysInternals Suite of tools.
Anyway, TaskExplorer shows you really a lot of info about a process, even which website it tries to communicate with. Maybe there is a connection required and your server is currently blocking it. Not all processes behave well when not being able to "phone home"...