Drag n drop functionality in Taxonomy just broke my site

OS - XP Pro Svc Pk 2
Server Apache 2.0.59
Drupal 6.4

Taxonomy menu also installed, also Token and a few others.

The sequence of events was this:

Adding terms to a new vocabulary as follows:

vocabulary
branch term 1
term 1a
term 1b
term 1c
branch term 2
term 2a
term 2b
term 2c

I then added another term intended for branch 2 and forgot to set the parent.

I went to List (of terms) and used the widget to drag the new term under the "branch term 2" tree.

Drupal timed out and returned a blank page with error messages that I unfortunately didn't take notes on. I believe they said that drupal timed out.

I hit the back button to go back to the term list page.

I hit "edit" to open the term and assign it to the "branch term 2" parent.

I noticed then that the administration menu was missing at least half of it's elements.

I've rebooted, cleared the browser cache etc but to no avail.

I can't get to modules or taxonomy any more.

The site is broken.

Please advise. Much work will have been lost.