I see no popup on Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910. Please check your settings.
This sounds like recently fixed bug 259117.
WFM on Mozilla/5.0 (Windows; U; Windows NT 5.1; rv:1.7.3) Gecko/20040913 Firefox/0.10 Either Resolve Duplicate of 259117 or Resolve Worksforme
*** This bug has been marked as a duplicate of 259117 ***