Well, this is weird!
I tried DCS update 2.7 now on two Win10 pro PCs. One is a I7 CPU, 16GB RAM and GTX 1080/8GB and the other new one is a I9/32GB RAM system with a RTX 3090/24GB.
On one system DCS crashes each time when I spawn the Viggen (and be sure, I applied all the above proposed repairs). Though with all other aircrafts there is no problem, no crash!
On the other system DCS does not crash at all, even when I span the Viggen!
So, now guess on which system DCS crashes ...
... aaawwh, it's the new system with the I9 CPU, 32GB RAM and RTX 3090/24GB!!
Waiting for a patch, whoever brings it up (ed, nvidia, heatblur, ...)