The song you're probably talking about is Ragnarap by The Happy Planets. If you're talking about the patch, I made it. I'll even explain it!
First I opened up the patcher as a PE executable in IDA Pro, checked the Analysis box in the first window, and then just clicked next until it started analyzing. I knew the error message that was thrown, so after it was done analyzing (doesn't take long), I went to Search > Text and typed in "BGM not found." That gave me this result:
Right click on the variable (line with "aInvalidEntr_19 db...") and select "Chat Xrefs to." That gives you a small flow chart with a single function: _WinMain@16_0.
Go to the Functions tab and scroll down until you find this function. Double click it on the list and it'll bring you to the code. Scroll down until you find the reference (it's a ways down). It's easy to find as the text will be in a comment next to it.
It should be obvious here what needs to be removed, but in case you're not sure, it's the call to MessageBoxA. If you select that line by clicking on .text:00413AA1 (or whatever yours is, if it's different), then click the Hex View tab, it'll give you exactly what you need to edit.
Now, if you've ever used Windows before, you'll know that lots of software makes lots of calls to MessageBoxA. This means searching for that little hex string is not a good idea. So take note of the
offset at which this code resides. In my case it's 00012EA1. So now open up the patcher in a hex editor and go to that offset. In Hex Workshop, it's Edit > Goto.
Now just NOP out all six bytes.
Save and you're done.