To be able to fix this error and login to the admin panel, you will need to edit a single file. I will be pointing you to go to "Line 60" or otherwise, and to do this you will need a text editor that has line numbering. A good free version would be Notepad++. Go ahead and download that and use Notepad++ to edit the file as mentioned below.
You will need to open the file /modlets/rssreader.php and go to line 60.
Line 60 looks like:
ini_set( 'user_agent', 'qsf-rssreader' );
To fix this change that line to:
@ini_set( 'user_agent', 'qsf-rssreader' );
Notice all I did was add an @ sign in front of ini_set
And that's it, it's quite a simple fix for a full stop error!