I'm seeing (a few) PSA's and wrong-sized ads on some pages today.. for example a 250x250 is showing a banner even though the code says 250x250 ... anyone else having trouble?
I was seeing PSA's and blank ad spots in the homepage of one of my sites last night. But its working fine at the moment.
I just checked the pages where I have used 250*250 ad unit and everything is OK. May be some thing is wrong with your PC and may be your hosting.