Old drivers probably, this happens a lot in OpenGL applications if you have old drivers or not enough video memory, even in commercial games.
If you think it's a bug then provide a very simple test case that demonstrates this issue and how to reproduce it then we can probably get around to fixing it.
ShadowMapping for Irrlicht!: Get it here
Need help? Come on the IRC!: #irrlicht on irc://irc.freenode.net
Or No drivers at all!, I had this issue and it turns out the video card driver was not installed so it used the defualt MS one which ran in REF mode(bascially software rendering by the driver).
"Irrlicht is obese"
If you want modern rendering techniques learn how to make them or go to the engine next door =p
Oh yeah, I've read OpenGL 1.5 in the OP Maybe it's just that. check the console (again) for the OpenGL version (and maybe post just the whole console text)
I have the same problem when using OpenGL device on my laptop (ancient Unichrome videocard, might be part of the problem). There are no visible textures at all and I'm not sure if it is a driver problem since all the other OGL software works fine. I think it still worked with some older Irrlicht releases.
Here's the programs output:
Irrlicht Engine version 1.5.1
Microsoft Windows XP Personal Service Pack 3 (Build 2600)
Using renderer: OpenGL 1.2
VIA/S3G UniChrome Pro IGP/MMX/SSE: S3 Graphics
OpenGL driver version is 1.2 or better.
GLSL not available.
OpenGL 1.2 often lacks the proper texture formats (BGRA _REV things). Maybe check the supported OpenGL extension with the ozone3d GPUCaps tools. I already have some texture conversion code in the ogl-es branch, just need to clean this up and merge into the other drivers in order to cope with unsupported formats.
I switched to Irrlicht 1.5.1 and it fixed the blank texture problem. But still the game is incredibly slow. It might be old drivers, its opengl 1.1 for sure. I'll change them and see what happens.