Help with recording demos?

Hey everyone,
I have been interested in recording gameplay for a while now and am now beginning to start with recording source games with demos. The problem is that whenever I am in DarkRP and press the F4 menu, on the demo it appears to be just a blank, grey box. Is this an error or does this happen for everyone? Also how can I record what I am typing in the chatbox? I don’t want to use Fraps or another recorder due to lag. Could anyone help?

Probably your computer

Also, Fraps isn’t really as bad people say it is. I spent about a month using and thought about deleting it, but after that is started working fine. It’s what goes onto your screen that makes it lag. Which also is probably your computer’s fault.