"Enter" key does not POST in forms in certain case

[Joe McDonagh]

Description: Ubuntu 8.10
Release: 8.10

firefox:
  Installed: 3.0.5+nobinonly-0ubuntu0.8.10.1
  Candidate: 3.0.5+nobinonly-0ubuntu0.8.10.1
  Version table:
 *** 3.0.5+nobinonly-0ubuntu0.8.10.1 0
        500 http://us.archive.ubuntu.com intrepid-updates/main Packages
        500 http://security.ubuntu.com intrepid-security/main Packages
        100 /var/lib/dpkg/status
     3.0.3+nobinonly-0ubuntu2 0
        500 http://us.archive.ubuntu.com intrepid/main Packages

What I expect to Happen:

Go to google.com, enter a search phrase, hit enter, and it POSTS.

What happens instead:

Go to google.com, enter a search phrase that ISN'T auto-populated in the dropdown from google, hit enter, and nothing happens. HOWEVER, if you enter a common phrase that does come up in the drop down, like "cute puppies", enter works.

[Joe McDonagh (joseph-e-mcdonagh)]

BTW, I am on a 64 bit OS.