(I tried to post this at the ED forums, but I can’t figure out how to use images, so just linking to here as quickest):
I think I can recreate this reliably without having to re-install Steam. It looks like it is caused by a timeout on the SteamVR side when VR reprojection is used with DCS (what is called Motion Smoothing on the SteamVR side). Here’s the steps for a Reverb using WMR for SteamVR and stand-alone DCS. I don’t think this is the only issue on that stack’s side, but it was the one causing my crashes as going back and forth between this one setting can cure the crash I was getting.
- Access the new WMR SteamVR settings dialog here (note: this was introduced Oct 2020, about the same time people started having issues on this topic and was intended to replace editing config files on the WMR side).
This can be done by clicking down the hand controller thumbstick on either controller. (sorry about the mouse art arrow 
)
- Access the ‘Graphics’ section and set the ‘Default SteamVR app motion reprojection mode’ to ‘SteamVR per-app setting’ (from the default of 'Disabled)
- Start DCS (so as to make it an app that SteamVR can see and provide settings for, otherwise it is not listed)
In the SteamVR desktop dialog (or you can do this in VR, desktop steps shown) access the ‘Video’ section and then the ‘Per-Application Video Settings’. Because DCS is running it’ll be the default selection:
(Note: hamburger/three lines menu on the left provides access to ‘Settings’ menu)
Settings menu, with ‘Video’ tab selected. Use the ‘Per-Application Video Settings’
- Because DCS is running it’ll be the default selection. Put the ‘Motion Smoothing’ setting to ‘Enabled’ (from the default of ‘Use Global Setting’)
- Close the dialogs and settings. Close down DCS and restart it. You have to restart DCS fully to enable this.
With those steps above from a clean Steam/SteamVR install I can reliably recreate the ‘SteamVR has encountered a critical error’ using the usual ‘stress DCS under load’ steps that others have described, e.g.
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Use the Syria map, as that uses maximum VRAM and needs paging more frequently.
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Use a mission either in MP or with lots of scripting, something that puts load on DCS.
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Change views, F10 switch cockpits etc.
I realize these steps aren’t ‘clean’ from a QA point of view, and the time to cause the crash can be up to 10 minutes of play, but it’s the nearest I got.
So my theory is that my issue was something that changed about Oct 2020 in how SteamVR handles reprojection and how DCS sort of times out when under load past a tolerance that causes the middleware to crash out.
I reported it on the SteamVR side here - DCS World and SteamVR has encountered a critical error :: SteamVR Bug Reports
Like I said up top, I doubt this is the only issue on the jenga tower of this stuff, and others might get the same crash for different reasons but it is the one I can reliably recreate on the set-up I have. I now run without reprojection (which is a shame as targeting 45fps is needed in VR for DCS on what I have) but it’s great to have stability again, as I sort of dreaded the ‘a crash is coming and I’m about to do something important’ feeling in MP.
Hope that helps someone else.