In the example link below the "mcp" is changed into MCP (acronyms changes lower to uppercase), and I think it should n't do that inside codeblocks.
In post history (while posting this is not happening, I'm talking about the second use of "mcp" in the piece of code)

http://www.icyphoenix.com/show_post.php?p=55450

It's very tough to allow Acronyms only outsite CODE BBCode.

I suggest to disable Acronyms when you intend to use Code in your post.