Using WP-dTree 3.3.2 I run into two problems:
1.) Validation failed, solution here
2.) Expanding or collapsing crashed my .css floating layout. This was due to missing width style definition. Adding this solves the problem:
#dtreec, #dtreea, #dtreep, .clip {
width: 100%;
}
Just wanted to let you know, in case you have a similar problem in your theme.