the mainfile.php seems correct.
I've found the problem.
I use php-stats, and it seems to conflicts with xoops.
When I exclude my IP from the count, its OK, when I include, then I cannot login anymore.
$replacements = array("\1<a href="\2://\3" target="_blank">\2://\3</a>", "\1<a href="http://www.\2.\3" target="_blank">www.\2.\3</a>", "\1<a href="ftp://ftp.\2.\3" target="_blank">ftp.\2.\3</a>", "\1<a href="mailto:\2@\3">\2@\3</a>");
$replacements = array("\1<a href="\2://\3" target="_blank">\2://\3</a>", "\1<a href="http://www.\2.\3" target="_blank">www.\2.\3</a>", "\1<a href="ftp://ftp.\2.\3" target="_blank">ftp.\2.\3</a>", "\1<script language="javascript">var id='\2';var host1='\3';var host2='';document.write('<a href="mailto:'+id+'@'+host1+'.'+host2+'">'+id+'@'+host1+'.'+host2+'</a>');</script>");