Had this problem on a local install with 4.1 also.
This worked for me:
in wp-includes/update.php
go to line 24/25 which reads:
`if ( defined(‘WP_INSTALLING’) )
return;`
and re-format onto one line like so:
if ( defined('WP_INSTALLING') )return;
I very much doubt this is doing anything in particular, you could more than likely format any line you wish, but the action of saving it appears to fix the problem.