Google repeat errors in Performance log accessed by clicking WEI score link at Computer>Properties, then clicking Advanced Tools. Look for cued issues at top of Tools page, Generate a System Health Report.
Click the Advanced link at Computer>Properties then in Performance>Settings uncheck visual effects for fading, sliding, dragging intact which may be sufficient. You may already be warned about this on Tools page.
Whenever there are hangs in Windows 7 I would also test my RAM with memtest86 for 5-6 passes and test HD with maker's diag/repair full CD scan.
Windows 7 troubleshooting fundamentals: Computer lags every couple seconds