I also just signed up for diigo, and I find that IE freezes when I use the IE right-click option "open page in new tab" and also when I try to access a page via a URL in another application. Both of these features worked before I installed the diigo toolbar.

My OS is Windows XP Pro and I am using IE7.0.5730.11. I always run on an administrator account.

I have a bunch of IE add-ons and will email screen shots to the email address given in reply #2.