Are you still using Windows 7 RC? Here is important information from Microsoft about functionality and expiration dates of Windows 7 RC and beta.
Effective from February 15, 2010, the expiration process starts. You will receive an expiration notification in the task bar one time per day, Then one time every four hours and then one time every hour.
Effective from March 1, 2010, your PC restarts every two hours. Your work will not be saved.
Effective from June 1, 2010, Windows 7 RC expires. You will see a black desktop, activation screen and restarts every 2 hours. Further information available at