[headboff]

This is a server issue and is not being caused by anything on your computers.

Web applications such as bulletin boards run a lot of their functionality "server side" to enable things like logins, permissions, interacting with a database, rendering layouts, etc. What's happening here is that the code running server-side is unable to allocate the memory it needs to perform the task you happen to be asking of it at that moment.

Why doesn't it have enough memory? Web servers like this one often run tasks in the background.
Tasks consume memory like any other program. Also, some tasks (such as searching for a keyword) can consume more memory than simply displaying a thread. If one or more of these tasks happened to be running at the time, consuming memory that would otherwise be used to fulfill your request, that memory pressure could be the cause.

Without having more information about the server, this is conjecture though.