I solved it!
Had the same problem. Empty Settings Page, no Log Infos.
After debugging code for a while, i narrowed it down to piwik/plugins/UserCountry/LocationProvider/GeoIp/Php.php line 72:
The nasty @ in $location = @geoip_record_by_addr($locationGeoIp, $ip); was preventing a decent log dump. After removing it, i got:
PHP Fatal error: Call to undefined function mb_internal_encoding() in piwik/libs/MaxMindGeoIP/geoipcity.inc on line 130
=> missing mbstring php extension.
I called my sysadmin to install it quickly -> works!
So I guess you Piwik guys need to check for mbstring extension on Geo IP Setings Page?!