error after impex import
 

After I've imported my old forum with ImpEx and installed vbseo I got this error:

Warning: mktime() expects parameter 4 to be long, string given in [path]/includes/class_userprofile.php on line 260

This is on top of the page of every imported member. How can I remove it?
I am not sure if this comes from vbseo or vbulletin