Preview Button Not Working on Post Creation Page

Using WP 2.9.2 — not in the popdown menu.

The Preview button on my lifehack blog stopped working when creating posts. Strangely, when I “save as draft,” the yellow shaded area at the top brings up a link that says “preview post.” If I click that link, the preview window pops up in a new tab as usual.

I tried deactivating every plugin and changing the theme to default. No change in the problem.

I have blog setup blog that has an almost identical setup, but the preview mode works fine.

In addition to that problem, the first blog also won’t show tables created with wp-tables reloaded, but the other will. Don’t know if that’s related.

Any ideas?