I installed a new graphic card (Radeon HD 5850) with latest drivers.
Today I noticed that glReadPixels does not work anymore when I enable multisampling although I downsample the multisampled FBO to a normal buffer using glBlitFramebufferEXT.
This was working fine on my old NVidia 8800 GTS and on the Radeon in my laptop so I have no clue what is going wrong.
Windows 7 x64 - OpenGL 4.X (but I use the old 1.X/2.X context)
It works if I disable the multisampling. On the other cards it works in both cases.
Help is really appreciated!