Glad you solved it...here's a couple of things you could have tried..i'm only posting this because it took me ages to compose!
You could try a couple of things depending on what modifications you have made after the crash?
Change the extension of the corrupt capx to '.rar' and open it with Winrar.
1, Create a texture with whatever graphics software you have installed, and save it into the relevent project texture folder, naming it 'gatewayexplosion.png'....then try to run it?
or
2, Check the folder "C:\WINDOWS\Temp" you might find the project in this folder under a different name....or a copy of the missing texture(renamed).
If you can find a copy of the texture in the temp folder(probably renamed)...drag it out out, rename it to 'gatewayexplosion.png'and drop it in the relevent folder in the 'caproj' texture folder.
Hope this helps(and makes sense)