Why would my baked lights only render for a few seconds?

Hi there,

I'm having an issue with Unity 5's baked lighting system. I believe I have followed the official manual on baking lightmaps to a tee but I get weird results. For the most part the lights don't show at all. If I change something about them (anything about the lights or anything about Baked GI in lighting window) then they seem to show for a second or two, but only sometimes. If they show up in my scene view and I immediately hit PLAY then they stay visible for the duration of the play session. They disappear again shortly upon stopping the simulation.

My best lead is a problem with files of extension ".exr" I believe the generated lightmap is of this type. I cannot open the file "LightMap Snapshot" but only receive a warning to check external application settings. I thought I should head over to Default Programs to see if Windows 7 could tell Visual Studio to open .exr files but it doesn't even seem like the operating system is aware of these files. I'm not very familiar with setting default programs for extensions not in the list included with windows, if it's even possible.

Also, I'm using deffered rendering path.

Has anyone encountered such a problem or know a fix?

thanks!