getimagesize() error

I get this error:

Warning: getimagesize() [function.getimagesize]: Filename cannot be empty in /home/mydomain/public_html/inc/images.inc.php on line 569

when members join

and

this error

Warning: getimagesize() [function.getimagesize]: Filename cannot be empty in /home/mydomain/public_html/admin/global_settings.php on line 800

when I make a change to admin setting

Any suggestions are greatly appreciated.

Which version of dolphin 6.1.4 or 6.1.6 ?

what is the code at the file path/line # that it's referring to?

Is this a base install or a modified install?

If modified, what mods do you have on the site?