Run the Windows 7 Memory Diagnostics Tool manually

If the Windows Memory Diagnostics tool doesn't run automatically, you can run it manually.

1. Open Memory Diagnostics Tool by clicking the Start button, and then clicking Control Panel. In the search box, type Memory, and then click Diagnose your computer's memory problems. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

2. Choose when to run the tool.

From Microsoft: Diagnosing memory problems on your computer