I frequent 2 forums--BP.net and another one. They seem to use the same software as a base. Sometimes, when I'm browsing both of them at the same time (I often will open threads in multiple tabs, then read through them), both sites will time out while opening pages at the same time. I'm not sure if it has to do with the software, servers or what. Usually refreshing a few times solves the time-out issue for me.