In 107 and the previous build I've still been getting occasional graphics freezes for about 10 secs with sound still running, then the game continues with textures messed up. I think the build before that (or was it the one before that(?)) didn't have it. Turning off shadows has always stopped it when it's present. Few others seem to have this so I suppose it must be my system, but rF2 is the only game that does it.
I would have assumed that was a graphics card overheating or failing... Are you able to monitor your temperatures on the GPU? If so, please google for 'safe temps' for your card and compare.
I monitor temp and control fan with MSI Afterburner. Temp's never above 65 degrees C. England ain't hot at the moment. In the past I've run iRacing at much higher temps. One occasion it happened when I left it for a few hours on the 'race' screen - the one with the small replay window top right. Can't have been getting hot then, surely. When released from the start rf2 did this, then couple of builds ago it behaved for one build, and now it's back again.
I do still think your gfx card is failing due to the description of the issues, but if it's not, it's not. The only thing I can suggest really is to make sure the drivers and DX are up to date, and then uninstall and reinstall (and update) the mods you have. That may help to refresh shaders, etc.