humm... nope. doesn't seem to fix the situation (disabling default widgets).

Here's what I'm seeing and maybe this'll help w/the bug log:

I have uncaptcha and default widgets plugins.  In 1.5 I had no issues with these two together but now i'm having issues with both beign enabled. When uncaptcha is enabled, default widgets will not work and users are forwarded to a blank page. So some test users registered without uncaptcha enabled, other test users registered with uncaptcha enabled.

For users that were able to successfully register and had default widgets generated for them, I was able to delete them as long as I had 'uncaptcha' plugin disabled also.

For users that were generated with 'uncaptcha' plugin enabled, default widgets has an issue and no widgets were actually generated and I cannot delete these users no matter what.

Maybe this'll help?

How familiar are you with Elgg's database schema? You could look up the entity with guid 3291 and see what the subtype ID is and then check in the subtype table to see what subtype string is. That should give you a clue where this object came from. 

Following up on Cash's advice, you can find more about entities here and the database schema over here. You should also leave Brett a note asking him to take a look over the thread if he has a moment. He marked the bug active in the tracker and wrote the plugin that seems to be causing the conflict. He might have a reasonable idea of how to address the issue or at least understand what is causing the issue you are encountering.

Casey