The "out of memory" pop-up says your'e running out of the limit on private committed memory—a type of virtual memory. Not that you're running out of RAM (physical memory). It doesn't matter how much available RAM you have. Having lots of Available RAM does not allow you to exceed the commit limit. The commit limit is the sum of your total RAM (whether in use or not!) plus your current pagefile size.

Conversely, what "uses up" commit limit (which is mostly the creation of process-private virtual address space) does not necessarily use any RAM! But the OS won't allow its creation unless it knows there is some place to store it if it ever needs to. So you can run into the commit limit without using all of your RAM, or even most of your RAM.