I was just testing the forums registration form to see something but obviously didn’t register as a new member!
When you go to Register using Opera 11.01 on Microsoft Windows 7 Professional it comes up with the vBulletin Message: You have left a required field blank. Just after clicking the check box for “I have read, and agree to abide by the SitePoint Forums rules.” Heh.
Also, is the Referral field still a part of the Registration form, and if so, does that still work fully?
I was having a similar problem registering using MS Internet Explorer 8.
I would check the acceptance box click the Register button then be taken to a page telling me I had left one of the required fields blank.
I tried to register seveal times over several hours always the same error.
Then in browsing around I found your post. Reading it made me think, perhaps I should try registering using the new Firefox 4.0.
That worked!
When I got the confirmation email, I clicked on the link. From within Outlook. Similarly, it did not work. I tried it a second time and then was told I was already confirmed.
So now that I was informed that I was registered, I tried to respond to this thread using IE 8 and I was told that I was not logged in yet. However, up at the top right corner of the screen it showed my screen name right next to the Welcome.
So I tried a second time.
Clearly something is wrong with the code for your registration system.
It may be an Opera and and IE detection problem but your system does not seem to be able to reliably tell what responses or communications have occurred.