Very odd, eMail sender listed as _, plus more..

[zefyx]

So, something weird is happening, regardless of having my webmaster@example email in contact details, everytime someone is emailed from my forum the sender is listed as _. Also, when someone registers, at the top left hand corner of the navbar right above "Thank you, proceed to edit Profile, blah blah" it shows a white _. When I receive the New User emails, the referrer is listed as _, unless the user specified a username in that space.

Any ideas? This is quite annoying.