try official viewer? maybe there's something in this version of firestorm that doesn't play nice with something in his computer? (odds are unfortunately high that official will have the same problem if that's the case, but it's at least a thing to try)

also, how long ago was it working fine? anything update in between to change things? either FS update or windows, graphics driver, etc?

Allegory: He had it working a few days recently and before that (a few months) it was just fine. And yeah, FS had an update, but he did run the older version alright for a bit. I'm wondering if they did something where it made the older version obsolete?

they do disable a couple of versions back, LL kind of requires it so new features get support.

i'd personally suggest he try installing official LL viewer next. it doesn't share the same folders and stuff that even a clean install doesn't get rid of, as well as having slightly different code. if that works, FS may still be possible to get working by cleaning out the rest of the stuff in case there's something a clean install didn't get...if it

doesn't work, he probably has a deeper compatibility issue with the current code base.