Main page Cialis spam

I’m having an issue where there is spam (mainly Cialis ads) are appearing as plain text in the middle of my main blog page (www.blueseatblogs.com).

It doesn’t show up on all computers (it isn’t showing up on mine for example), but I’ve been sent screenshots that it is there.

I can’t include images, or else I would include a screenshot of the spam that was sent to me from a reader. It appears to cover the right side of the blog, across authors and the poll.

Any idea on what this is/how to get rid of it please?