First let me say that I think your plugin is great. I did find what I think is a bug today, though.
When I manually position the ads, using <!--Ads1--> for example, the paragraph after the manual insertion code gets its beginning <p> tag stripped out.
The pages where ads are being automatically inserted according to the rules defined in the admin console are working fine. But every one of my pages that uses manual ad positioning has HTML validation errors with missing <p> tags, and every missing <p> tag corresponds to a paragraph after manual ad positioning code was used.
Thanks in advance for your assistance with this.