i'll go ahead and preface where this thread is going probably (when nitro2k01 reads it). 

make a backup copy of your sav file now.  and, keep the file safe.  there is the chance it can be repaired, this has been done in the past.

but, nitro2k01 (the only one i know that tried these things, or offers to at least) will need the sav file to do this.  so, if you want, go ahead and get that prepped, and if he reads this thread that will be done for when he requests it.

(i don't mean to volunteer him like this, but he's the only one i can think of that knows the file structure intimately enough to help out with this, and has shown willingness to do this in the past)

regardless, you ought to make a backup regularly.  with any type of flash cart, this is important.  any type of most anything in a way...

@Vex -- the issue you are having with more complex songs may be a problem with the tables.  try running problem tracks on a gameboy color and see if the issues go away.  the DMG CPU may not be quick enough, its a problem for everyone.  just a thought...

Yea man that's happened to me countless times. Most of them before i ever learned how to back up my stuff on the comp so i lost 20 songs and gave up writing for almost 6 months because of it. As for fixing that one song I do not know a way. I've had corrupt files happen and you just have to delete them. Ive notice it happen more so when im near 67/BF blocks used which is only about 7 tracks I think. Also the more complex a songs wav channel is, I've noticed major issues with the 64MB carts, this may just be coincidence but eh. It feels that way.

Well I don't have any advice for you except get in the habit of backing up often and making multiples, I actually back mine up almost everyday I touch my cart just as a safety precaution and definitely when a track is done. Best of luck man.

So, it would seem that I would be just my luck that my track MINT's data on my 64MB Smartcart got all sorts of messed up.
All the instruments got set to 00 and all the cmd and tables settings have obscure numbers and glitched out symbols.
The weird thing is that it is ONLY this file on the cart that is behaving this way.
This really sucks because this was supposed to be my finale track tomorrow night at a show.
I've accepted the fact that it's probably lost forever, and I can always rewrite it, probably improve it in many ways too; but if anybody knows of any sort of fix it would be great!