Random post-installation errors

OK, not really completely random, and not really post-INSTALLATION. More like not entirely consistent error messages after Drupal RE-installation. Here's the story:

My database was pretty slow after having installed and uninstalled 20 or so odd modules to see what they did. Had a lot of blocks and aggregation too. Really could have been anything. I come from a Winblows mindset, so rather than putzing around with troubleshooting this, I decided to backup up everything, wipe, reinstall, and import my files and ONLY PARTS of the database that I thought I'd need.

It actually seems to have gone rather well. I have all of my data back. The site is zippy. But every now and then, mostly when I'm doing admin things like adding modules or mucking in their config pages I get the error. Of course, all I've really done so far has been admin type stuff.

Here is the warning I get:
user warning: Duplicate entry '95' for key 1 query: INSERT INTO menu (mid, pid, path, title, description, weight, type) VALUES (95, 1, 'postcard', 'Postcards', '', 0, 20) in /path/.to/my/drupal/installation/root/includes/database.mysql.inc on line 172.

Looking at this as I type, I think I've figured out the answer. In addition to importing all tables with these prefixes; audio, comments, files, forum, ljxp, node, profile, role, tasks, url_alias, users, video; I also imported the MENU table. It seems obvious now that that must be my problem. Am I right? Will it be okay to drop this table? Does it get recreated?

In the process of researching this exercise, I found no documentation on reinstalling while preserving just your data (not the whole database). Is this worthwhile for me to write up once I get this fixed? Did I get all the right tables? I think I copied all the right files and folders. That's the same whether you're upgrading or re-installing. Any other comments?