EDIT: I downloaded the latest version of .NET framework and sure enough, the problem is fixed. Oddly enough, I had already tried this method to fix it the other day. *shrug*
Whenever I try to replace a file in BrawlBox (namely the CSPs), I get this error screen that if I try ignoring shuts down the program.
(http://i515.photobucket.com/albums/t355/chaoticfox9900/blah-4.png)
Apparently a file called System.Core is required to get this feature to function right, but I didn't see it when I Googled for it.
Have you tried reinstalling BrawlBox?
And what version are you using?
Redownloaded BrawlBox 0.63 and got the same result.
How did you solve it?
I edited the first post.