[Philip Stuyck]

checksum mismatch means you have wrong mod (car, track or both) version.
yesterday doesn't tell much, was it the same combo? if it was, you have problem with your install and should do an integrity check.

Can it be checked upfront?
I want to join the Aussiestig races and had twice a checksum issue. I downloaded the BMW mini and it worked for the first two races. Today the circuit is a standard track from AC, I believe, Nurburgring Sprint. So it has to be the car.
I am downloading it again, to install it again, but still it is weird.