I have no idea either. Happened again, downgraded to 0.59 from sourceforge, hasn't happened again since. May just be coincidence, but I haven't upgraded by graphics card drivers in quite some time; only thing changing is the OBS version. Annoyingly, it appears to be an intermittent problem. Hardest kind to nail down.
May just be an interaction with other software on the system (UltraMon/DisplayFusion and Chrome seem to crash each other and can't figure out why, for example).
Currently on Win7-64 SP1 Ultimate with a Radeon 6870 on Catalyst 13.4 drivers (Latest is apparently 13.12, so I really should update, it seems).