ET, I need halp :(

Ok, old problem has resurfaced. Whilst getting some test clips for opinions, I stumbled onto a n1 6man kill involving a airstrike, however using my movie config, after any airstrike's explosion happens, a whole bunch of artifacty white lines, which wouldn't look too good in a movie as you can imagine. What's worse is whilst recording at cl_avidemo 150, once airstrike is done and lines come, it locks up and quits et. Now this only happens on certain configs, so I KNOW it's not a gfx card issue, any ideas what commands could do that? I'm running 8800GTX gfx card btw. Thanks and much <3 :DDDDDD