WordPress MU

Hi, installed fine, integrated with mu fine - but when registering on WP site, I've got this error after the process:
WarningL in array(): Wrong datatype for second argument in
[my server]/nanothat.com/wp-includes/wpmu-functions.php on line 881
... this was a test signup without blog.
no problem logging in to the forum or on the main blog. Just this warning message I did not have before minibb integration to wp.
I had the developer of minibb install the forum with integration, and he said to ask in here.
Anyone know what I would need to do about this warning?
and to get rid of it?
url:http://nanothat.com/forum/
ps: don't get scared, have not customized colors yet
appreciate advise - thanks
michele

Greets:

Quick suggestion - Always do a search before posting about an error. there are no less than 4 threads on the subject along with a fix.

Hope this helps,
-drmike

thanks - sorry about that - you are right, will search more prezise next time first

Not a problem. (Actually I didn't even look at the name.) We won't burn you at teh steak this time. :)

I went a head and raised the level of the ticket. maybe we can get Donncha to fix this issue since it basically turns off all signups.

any word yet on the new fix so it does not turn off all signups?

Works for me. Donncha fixed it in 726.