W8 Virtual Memory
There seems to be a common fault with W8.x, it generates memory warnings well before any reasonable memory usage.
“Close Programs to Prevent Information Loss”
The error message has a bunch of google references.
I have put up a thread at answers.microsoft.com. The first suggestion was to check that paging is on and that the file is big enough. I used google to find out how, and it would seem that it is on. I have changed the settings to manual between 12 & 18 Gb.