I'm using several motherboards equipped in VIA KM400 & VIA CLE266 chpsets. All
of them use via_dri.so driver for hardware acceleration. 
I found out that after loading more than 100MB of textures "via_alloc_texture
fail" messages begin to appear. After some time (about 10-30 minutes) this
message is the last one before my app dies.
I've downloaded Mesa from CVS repository and found out, that there is no check
for return value of via_alloc_texture function. It is called within via_texmem.c
(viaTexturesGone).
The only thing to do is just to add a check for via_alloc_texture return value
and BINGO! - the app works for two days now...