Forum Sitemap Error
 

When I submitted my sitemap to google, it gave me the following error:

Quote:
Invalid date
An invalid date was found. Please fix the date or formatting before resubmitting.

After looking at the sitemap, I found the following line under quite a few of the entries:

1969-12-31T18:00:00-06:00

Can someone please help me find out what I need to do to fix this issue?