Not a bug
BYOND Version:471
Operating System:Windows XP Pro
Web Browser:Firefox 3.6.6
Applies to:Dream Seeker
Status: Not a bug

This is not a bug. It may be an incorrect use of syntax or a limitation in the software. For further discussion on the matter, please consult the BYOND forums.
Descriptive Problem Summary:

Music playing using browse_rsc fails every time after the initial.

Numbered Steps to Reproduce Problem:

Run the code.. If you have no MP3 handy, press Cancel (Built in MP3 in the RSC already)
Song begins playing.
Click the button again... Select cancel, or put in another MP3 it does not matter.
Song never plays.

Code Snippet (if applicable) to Reproduce Problem:

Expected Results:

Music to play when called more than just the first time

Actual Results:

First song call runs. Others fail.

Does the problem occur:
Every time? Or how often?
In other games?
In other user accounts?
On other computers?

When does the problem NOT occur?
Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit to download old versions for testing.)
Will test tomorrow if dev's feel it is necessary.

Close the game and reopen it and play again.

Sorry about the song choice, it's the only mp3 I had on hand at the time

browse_rsc() is acting as expected. If I change songs the file name you chose changes size. I submit that your embedded object HTML is the problem, since nothing plays at all for me. The method you're using to try to play the file may simply have some inherent limitations.
Indeed it was, sorry about the annoyance.

<OBJECT CLASSID="clsid:02BF25D5-8C17-4B23-BC80-D3488ABDDC6B"
<PARAM name="SRC" VALUE="MS_file.mp3"><PARAM name="AUTOPLAY" VALUE="true">
<EMBED SRC="MS_file.mp3" AUTOPLAY="true" CONTROLLER="false"

works fine. (Source: sound-embedding.html)