Try eliminating a few things that start up automatically at boot or run in the background.
Try increasing virtual memory.
Are you able to add RAM?
What operating system?
Apart from the suggestions provided by Peru Bob, it would be great if you could provide a little information.
- Is it a 64 bit or 32 bit version?
- Have you encountered the issue once or is it coming every time?
- Was there any other program running on the machine that might have consumed a lot of memory?