matroxfb problem: can't change resolution on boot

[enrique]

I have encountered a strange problem:
Normaly I'm running a 1600x1200 console using matroxfb, but now it only stays in 640x480.

I have tried to recompile my kernel and lilo but I can't get it working.

My /etc/lilo.conf looks like this:

boot=/dev/hde
default=Linux
restricted
password=bootpazz
map=/boot/map
install=/boot/boot.b
lba32

image=/boot/bzImage
label=Linux
read-only
root=/dev/hde5
append="video=matrox:vesa:284" # I have tried a lot of setting like 0x11c and so on.

cat /proc/cmdline gives me:

auto BOOT_IMAGE=Linux ro root=2105 video=matrox:vesa:284

dmesg says:

matroxfb: Matrox G400 (AGP) detected
matroxfb: MTRR's turned on
matroxfb: 640x480x8bpp (virtual: 640x26208)
matroxfb: framebuffer at 0xDE000000, mapped to 0xe0805000, size 33554432
Console: switching to colour frame buffer device 80x30
fb0: MATROX VGA frame buffer device

Can it have anything to do with I have changed the console fb setting once to watch a dvd with mplayer?

also I can change resolution with fbcon.

Kind regards enrique

[enrique]

If I compile the kernel with O3 it does not work, but if I use O2 it works fine ....