I don't think you're going to want to put a GetCalc() in your music routine. That can take a significant amount of time, especially if there are a lot of files on your calc. And I think the problem could be that you are not initializing the C variable, so there is a very large random delay before the music will even start.

How does it fail? And do you have a version of the code from before the music stopped working?

I initially checked for anything that might have been disabling the music in your code, but I couldn't see anything, so I figured I'd try to compile and debug it myself. After much sifting through the code and replacing forum-friendly characters with the real tokens so I could compile this on a calculator, the music appears to work fine for me. Are you sure the version of the failing source you posted is the version that isn't working for you?

That's not a good idea, the DispGraph command is *inside* the custom interrupt.

Someone else reported a recent issue about Wabbitemu, where most keys wouldn't respond at all.

Weird...
 
I hope you can get everything sorted out . Also check for closed parhentesises and brackets. I heard that in some cases, forgetting to close some can cause issues

Actually, the closing parenthesis are interchangeable and behave the exact same way.  In fact, they are sometimes implied when you don't see them.  For instance "Disp A" is actually parsed as "Disp(A" and thus you can add the unneeded parenthesis "Disp A)" and it will parse fine.  Since they are interchangeable, you can even do "Disp A}".  It saves code for me not to have to do all these formatting checks.