Vista users may get a bit of a shock when they click on anything marked with a red, green, blue and yellow shield icon. The screen will go dark and a message will appear saying 'Windows needs your permission to continue'.

In fact, this is not an error message - it's Vista's new User Account Control (UAC) feature, which acts as an extra layer of protection for your PC's inner workings. If the message has appeared immediately after you clicked on an option in Windows, simply click Continue to confirm that you want to go ahead. If the message appears out of nowhere, check the dialogue box to see which program has triggered it ¬unless you trust the program, click Cancel.