Are you behind a proxy server at work? If so, odds are you'll need this fix:
http://support.microsoft.com/kb/917952/en-us
Click here
I'm still not sure how this would effect auto-complete as it's driven from the iRuler.xml config file, not the downloaded templates (which is what the update the editor is finding). Once a day the editor attempts to phone home to devcentral to look for new updated iRule templates to add to the new dialog. When you use the share feature of the editor, we can turn them around and share them with the rest of the community.
Either way, it might be worth running this update from MS if you are behind a proxy server.
-Joe