If we assume the images are using 4 bytes per pixel, and assume there is no other baggage with them, then they equate to approx. 1.9MB.

I did once test what happens when you run out of physical memory and basically my app started to use swap space. But based on the fact that you only have two images approximately 1.9MB, then I'd say you have a serious memory allocation problem.

Is it possible to send me the source and exe?