Plugin text appearing in post excerpts

Hi everyone,

If a plugin is displayed at the top of my blog posts, text for that plugin has been showing up in the post’s excerpt when it is shared on other sites, (i.e. facebook, linkedin, bookmarking sites, etc…) I have had this problem with two plugins, Digg Digg (which shows “Buffer” in the excerpt) and WP Greet Box (which shows the entire welcome message before the post content). I ended up deleting the WP Greet Box plugin entirely to try to solve the issue, and although the files are no longer there, somehow the excerpt is still displaying the welcome message. I have written custom excerpts, as well as installed a couple of excerpt plugins, and these have not solved the issue. At the very least, I would like to fix the WP Greet Box problem as soon as possible, although a more long-term solution would be great as well. If you have any light to shed on this issue, it would be greatly appreciated.

Thanks in advance for your help.
-Stacey