First of all, how are you recording?
Is your machine of a good spec? Recording video is a very intensive process, especially at 1080p+ It may simply be that you're asking too much of your system to do everything at once.
I found that using fraps to record my game audio as well as my mic audio was quite problematic.. I got around this by using Audacity to record my mic instead, while leaving fraps to do the games. Give that a try?