i found this info for the admin loop but its for 3.0.3.2 , maybe its the same issue ?
You need to set your php time and mysql time the same. its deleting cookies to soon. You can fix this.
Open:
system/config/default.php
system/config/catralog.php
system/config/admin.php
Find:
$_['session_engine'] = 'db';
Replace
$_['session_engine'] = 'file';
theres also this thread about installing opencart that might help OpenCart Solution