Astonishingly, the so-called system restore feature in Windows 7 deletes restore points without warning when the system is rebooted. This forum thread on answers.microsoft.com shows some of the users who have experienced the problem. Today I did a clean install of Windows 7 Ultimate 32-bit (no dual boot), and noticed that whenever the machine rebooted after installing an application or driver, the disk churned for several minutes on the 'starting Windows' screen. Turns out that churning was the sound of my diligently created system restore points being deleted. Unfortunately I only found this out when Windows barfed at a USB dongle and I wanted to restore the system to an earlier state. This is an extraordinarily bad bug, which I suspect most Windows 7 users won't realise is affecting them until it's too late. Read more: Slashdot