Empty AdSense Blocks?!?

Hi all,

I’ve had my site up and running for a couple of months and have been running AdSense on it. It seems to have been working well, good targeting, etc., but just recently (last night) I noticed that it was having trouble filling up some of the AdSense blocks. See here:

http://www.fivecentnickel.com/

There’s one in each sidebar (smaller on left, longer on right) plus one in the main content following the first entry (for single entries, it’s located either at the ‘more’ tag or at the end for shorter entries). I also have a block of AdLinks in the left sidebar — these are not supposed to count against the limit of three AdSense blocks per page, and removing them does not help with the problem.

The problem seems to come and, almost always happening when I hit the front page with the ‘www’ prepended to the url, less often without it, and sometimes it happens, sometimes not on single post pages. This comes after having no problems, ever.

Anyone else experiencing troubles? Any suggestions/advice?

Thanks, nickel