[GtkGLExt] bizarre behavior on Core 2 Duo/1280x800

[z pekar gmail com]

Hi,
I have very strange stuff happening with my visualization. I use vtk and gtk...
 In my app I draw a plane with a cylinder normal to it. Everything is displayed
nice on my home desktop (debian/linux testing; celeron D; 1280x1024 pixel) my
friends desktops one with windows and amd 64bit CPU and another one
with Fedora and also on his windows laptop. But the same app with the
same parameters on my laptop (debian/linux testing; Core 2 Duo/1280x800 pixel)
displays the cylinder not normal to the plane but with other angle -
around 45.
while trying to run the app on my laptop that was compiled on my desktop I got:
./app: error while loading shared libraries: libgtkglext-x11-1.0.so.0:
cannot open shared object file: No such file or directory
eventhough it seems to be there:
find /usr/ -name "libgtkglext-x11*"
/usr/lib/libgtkglext-x11-1.0.la
/usr/lib/libgtkglext-x11-1.0.so.0
/usr/lib/libgtkglext-x11-1.0.a
/usr/lib/libgtkglext-x11-1.0.so.0.0.0
/usr/lib/libgtkglext-x11-1.0.so

What could it be???

thank you in advance