WPMU – Posts persist on front page after being deleted

I have a WPMU site running about 30 blogs, recently some spammers have registered for blogs and made several blog entries in their blogs.

I have removed the posts via the WPMU admin (logging in as admin/root and then deleting the posts, blogs and the users) but I have a problem – the posts still persist on the first page (the one that shows a feed of all posts posted in any blog of the WPMU install.)

When clicking on one of the deleted entries I receive the message “This user has elected to delete their account and the content is no longer available.” but the posts still persist permanently on the front page despite having been deleted, and I’d like to know how to make them disappear. They do not show up anywhere in the administration area (because I deleted them), no cache modules are installed.

I’m sorry if this is messy, I’m a pretty new WPMU user and might not understand everything correctly. Any assistance is greatly appreciated.