Punportal "Latest Posts" issue

I was messing around with the RSS Feed agregator, and mistakenly sucked down like 250 posts from Digg's RSS feed.
Oddly, the forum to which the feeds should post was not set up correctly (err, actually I deleted the forum)

The upshot is, I have 250 "latest posts" showing in my latest posts block, which lead to a bad/outdated link on my forum.

Now, test posts do not show up in the "last posts" block.

Can I reverse the effects of the 250 last posts ?