This can be a javascript issue. I was having this issue where I was not able to select "Settings" on the admin page. Everytime I click on settings and the page got refreshed. Later I found that there was a problem with the javascript call in my theme plugin.

This is how I suggest to check the issue:

1. Flush the cache and run an upgrade. If this does not help move to point 2.
2. Disable the plugin one by one and check if the issue is resolved or not. Once you identify the plugin that is creating the issue, discuss the same with the plugin's developer.
3. Lastly, you can also check you browser console to identify the issue.

Check this out

Modify the elggx_userpoints_annotate_create() function to check if the $object->name == "likes". If that is the case retrieve the entity getting liked (get_entity($object->entity_guid)) and then check if the owner of this entity is a friend of the logged in user. If this is the case, proceed with adding userpoints, otherwise skip it.

I checked start.php and files in   elggx_userpoints/views/default/elggx_userpoints  but I cannot find the owner entity logged in user file

$logged_in_user = elgg_get_logged_in_user_entity();

will fetch the user entity of the user logged in to the current session and assign in to the $logged_in_user variable.

You might want to take a look at the Elgg docs at http://learn.elgg.org/en/stable/guides/index.html to get some basic knowledge about coding Elgg plugins.