I've been experiencing this for a couple of weeks, but I'm thus far unable to pinpoint the cause.
Here's the result of running it in gdb:
[ws] Error in display.
[ws] Error code: 178 ( RenderBadPicture (invalid Picture parameter) )
[ws] Request code: 155
[ws] Minor code: 7
[ws] Modules: (NULL)
Program exited normally.
strace results in this:
open("/usr/share/X11/XErrorDB", O_RDONLY) = 9
fstat64(9, {st_mode=S_IFREG|0644, st_size=37949, ...}) = 0
read(9, "! $Xorg: XErrorDB,v 1.3 2000/08/"..., 37949) = 37949
close(9) = 0
write(2, "[ws] Error in display.\n", 23[ws] Error in display.
) = 23
write(2, "[ws] Error code: 178 ( RenderBa"..., 71[ws] Error code: 178 ( RenderBadPicture (invalid Picture parameter) )
) = 71
write(2, "[ws] Request code: 155\n", 24[ws] Request code: 155
) = 24
write(2, "[ws] Minor code: 7\n", 20[ws] Minor code: 7
) = 20
write(2, "[ws] Modules: (NULL)\n", 22[ws] Modules: (NULL)
) = 22
exit_group(0)
Long story short, I'm thinking that it might actually be an xorg problem rather than an MPlayer problem, but I'm not sure where to go from here. I've just now generated those two traces, so this is the first time I've really tried any serious debugging - I've previously just assumed that the problem was isolated to me :-)
This is using the build script at
http://rlworkman.net/slackbuilds/MPlayer/ (which allows MPlayer's configure to determine compiler flags and such, as recommended by the MPlayer devs).
Here are the circumstances in which I get the error:
First, play a video file (.mpg, .wmv, whatever). Let it finish or stop it manually - either one is fine. Right-click on the video window, and the expected new window outline appears, but MPlayer immediately crashes.