Sorry for missing this when it first came in. Some things you could try:
1. Can you build a library at all? Try the Targeted Method Editing tutorial, which will have you build a library. Does that work on your machine?
2. This can't be the entire message you receive. Try including a screenshot of the message or use ctrl-C when the message appears to copy its full text to the clipboard (not just the exception message).
If it turns out to be just your PD results, then we will need you to post the files you are building your library from. You can put them on http://skyline.ms/files.url
If you can't build any library at all, then this must be an installation issue, and you are encouraged to follow the directions for recovering from a broken installation at http://skyline.ms/install_recover.url
If after an installation recovery (or clean installation) you still cannot build any library, reactivate this issue with the new information on your situation.
Again, apologies for taking so long. Let us know if you solved this issue.