I had the same issue on my Ubuntu 7.10 boxes with FX5200 cards after the upgrade from 1.4 to 1.5.
As soon as I enable sound and/or music the client crashes with a core dump for an illegal instruction. Also all special effects like fire/magic stuff is not working.
In 1.5 all problems were fixed through a client which had been compiled on a Slackware box. Could this kind person please do this again for 1.6?
Any other help is also more than appreciated.
Thanks.
SJ
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PROBLEM PARTLY SOLVED:
The special effects need libpng3 installed. Installed it and they work fine now.
A VERY BIG THANK YOU TO QUA. He pointed this out to me.
The problem with sound/music is still there.