I got this message when i log in to adsense today... Error: We apologize for the inconvenience, but we are unable to process your request at this time. Our engineers have been notified of this problem and will work to resolve it. Why..this is normal for all?
Sometimes they're just down for maintanence - just try again in a bit. Startled me the first time that happened to me, too though...
Google is probably maintaining their website at this time. Unlike youtube they don't say when they will start at the top of the website but you will get the message when they are. I get this sometimes when i try to acess gmail but wait 5 minutes or so then it should be back to normal.