error which leaves me baffled

Hi, I have an installation of WPMU 1.2.1 on BP, the fact is that I stopped working the blogs, then upgrade to 1.2.3 and let BP of running the site completely unable to automatically reactivated BuddyPress, retrieve a copy up the day before and it did not work for me staying pure white, tried to remove and dump all database and backup files past and nothing still blank (inexplicably).

I went to the server logs or error log and I found that I had always given in all cases and releases the following error and I did not realize. The problem is that not it is due. Has anyone ever seen this situation or know it is? Thanks, that gives me the error in the log is:

[Fri Apr 09 13:35:10 2010] [error] [client 84.123.74.99] PHP Warning: require(/var/www/vhosts/"usuario"/httpdocs/wp-includes/compat.php) [function.require]: failed to open stream: No such file or directory in /var/www/vhosts/"ueser"/httpdocs/wp-settings.php on line 264

Any idea!!!

Thanks.