I registered a new gmail account and a new diigo account based on that email. Some days passed and then when I used diigo I saw the picture of a woman (still on my profile, didn't change it.)

There's zero probability I've uploaded that picture. I've never seen it.
Initially I thought diigo may be using some third-party avatar service, and that someone wrongly registered my email without verification, but that seems extremely unlikely.

The compromised client or account scenario is hardly imaginable. I can explain why, in private, if you don't believe me.

So... how come I've got some woman as an avatar? Is this the result of some freak bug? Is the image associated with any other account? is there an IP log of the uploader or of the changes to my profile?

Sincerely, I doubt that diigo staff would lose time with such an issue, but... this situation freaks me out, and I'd be really happy if you could get to the bottom of it. Please.

Well, I'm probably going to scrape my accounts because this freaks me out.

Just tell me, given your knowledge of the system, would this be something remotely possible or are we talking about never-in-this-universe-have-we-seen-such-lucky-neutrinos probability?