captaincupcake wrote on Oct 16^th, 2021 at 5:08pm:

I'm trying to reinstall the 737 Classic but getting a message telling me I need version 1003 (I think it was) so went to my profile to download the updated version but it only shows version 1000.

When looking at the files I have saved for the installion for all 3 models, 737-300 Base Pack, 737-400/500 Expansion Models, they're all v1.0 (csy37x_1000), with the update files going up to 1007. When installing them, you shouldn't be asked to install v1.003 to do so.
I'm not sure of a fix for this, but you could look at deleting/renaming the key_y373.dat file (key_y374.dat, and key_y375.dat for the Expasion Models if you have them too), found in C:\Users\<YourUserName>\AppData\Roaming\CaptainSim\y373 then reinstalling. This will require you to having to reactivate it/them. As I said, I don't know if that will solve the problem, but it might be worth a try.