Are you creating your windows with the CS_OWNDC flag?
For now, Intel has poor support for OpenGL. They have entered into a technology agreement with NVidia, so future cards may have better support. You may just be exceeding the capacity of the Intel Graphics Drivers.
In the past I've used the Mesa
OpenGL DLL to work around issues with their drivers. This may or may not solve your problem.
As a rule, I tell clients not to use Intel Graphics cards with OpenGL products.
I recommend NVidia or ATI.