Safari 5.0.2- Can't Open a new Tab

Hi,

I'm running Safari 5.0.2 on a MacBookPro running OS 10.6.4 .
For the past 2 days, I haven't been able to open a new tab.

I've tried command-t
File-->New tab
and I've tried checking my preferences.
I looked for an option to "enable tabbed browsing" but didn't see one-- I'm wondering if that option is outdated?
My software is all up to date.

I am able to open new windows.

Any ideas?

Have you installed any plug ins or extensions to Safari? Do you have Glims installed?