Firefox causing GL_FRAMEBUFFER_UNSUPPORTED

I have some code that uses framebuffers. While the code seemed to be debugged and working fine, I was occasionally getting strange GL_FRAMEBUFFER_UNSUPPORTED errors on some runs. After a while I discovered that if I had Firefox running in the background for a few hours, I would start getting this error. Killing the Firefox process lets my code start working again.

I didn’t have this problem under GL 3.0.0, but do under GL 3.3.0 (or maybe it’s the latest Firefox release). Anyhow, I suspect the answer is ‘don’t use Firefox’, but if anyone has any other insights as to why this may be happening, I’d be interested in knowing.

Maybe video card resources are used by the browser, reducing the video ram available for FBO ?
http://hacks.mozilla.org/2010/09/hardware-acceleration/