[SDL] Xlib: unexpected async reply

[root]

Xlib: unexpected async reply
i have 2 pc: the first witn suse8.1
the second with mandrake 9.2
I retrieve this error frequently only in mandrake 9.2 and very rarely on
suse.
Xlib: unexpected async reply (sequence 0x34)
0x48 0x2a ecc....

i see that in threaded routin(like timer)i cannot use some function of
sdl.

what are these?
i use SDL_Flip,SDL_RemoveTimer,SDL_AddTimer in my own timer function.
is this the error?

thanks.