I have the white square problem. My object icons such as inventory items or other items are a blank square. In my case they are tan.
The label of the object is ok when moused over. You can right click and see the items properties. You can also drag the squares around. Only the icon is missing.
I tried the 'delete the ; in front of Video.OpenGL.UseExtension.GL_ARB_texture_compression = false' fix, but no help. From Caarrie's referral above.
Also, I have no sound, and I cannot put check marks in the sound or other config boxes, don't know if related.
Vista Home Premium 32 on a 64 bit laptop.
Intel Mobil 965 express video.
2ghz intel duo cpu dual core.
4G memory
Sigma tel audio
*update:
I had to jump through copy, rename, permission hoops. I was using notepad, tried wordpad and editing on the desktop, copying to folder, renaming old one etc. etc.
The fix above works, (for the icons, I still have no sound, and I cannot check items in the options box), just have to be sure it "takes". Windows is so painful to come back to. Long live Linux (PCLinuxOS).