I'm not sure what you mean by "It executes the code from within the block". Can you explain that any better? When I put in some html, the code is saved just fine. Are you using the editor? If so, there is a little button that looks like this <> that you can click on to see the HTML. You can then click the "hide html" button to change it back to the editor.
If you are having some problems with a particular piece of code, please post that code using the BBC code tags in your next reply so we can test it.