New Accounts error message (MU2.8.6)

I have a clean install of MU2.8.6 and when a new account is created the following error is show:

Warning: require(../wp-load.php) [function.require.php]: failed to open stream: No such file or directory in D:\instancesintime.com\wwwroot\wp-admin\upgrade.php on line 18

It is a new Install and the email is sent ok, when the user confirms the account the error happens and no password email is sent, although the blog account is setup.

The latest plug-ins were avatars and photoQ photoblog, I have already re-copied over most of the install files again just in case.

Anyone have any suggestions, i have disabled registration for now.

Regards

David