This error occurs when the page file on the system partition is set to a value that is less than the size of physical RAM. To stop this error message from appearing, simply increase the page file size until it is larger than the amount of RAM that you have.
Ideally, page file must be size of the physical memory + 12MB, if you want NT to write the memory dump in case of a crash. In your case, if your system partition is 5GB, I assume it's an NTFS and if it's systemroot, it's your boot partition too. Check your page file configuration for system partition, it must be 512MB + 12MB. Reboot and everything should be fine. If you keep your page file on system/boot partition you should be able to save the crash dump.
I recommend setting the minimum and maximum value same to avoid fragmentation of paging file and to save system resources which NT might use while expanding and shrinking the file.
One more thing, for performance gain you can move the page file off the system partition to some other partition, preferably to other hard disk.
Happy hunting...
Mubashir