SDL, suddenly music functionality stopped working!

[corge]

The problem started with that I got a lot of errors about missing header files included from SDL_mixer.h when I attempted to compile my projects.
I looked in the directory of this file, and all header files were missing except SDL_mixer.h

Resolved this by compiling and installing the base SDL library package.

Programs that got recompiled and were able to play music before suddenly produced no music, but sound effects worked. However, old binaries that were compiled prior to the issue with the missing header files played music fine.

What the heck is this? I get no errors, nor warnings; none at compilation, none on execution. The kernel pool (dmesg) is clean.

There is also another strange issue, which perhaps has nothing to do with the first issue.

x86_1$ ./fire
XDM authorization key matches an existing client!Couldn't initialize SDL: Couldn't open X11 display

This might be related to a bug in XDM from searching on Google.

[Rubberman]

You installed new SDL binaries (shared libraries) that are probably incompatible with the ones that used to be there. You may be in for a long process to sort this out...