Add theme and get this error?

I installed the Salient theme but everytime I do i get this error message:
Fatal error: Allowed memory size of 41943040 bytes exhausted (tried to allocate 491520 bytes) in /home/eproadmin/public_html/wp-admin/menu.php on line 267

I checked the menu.php file for the theme and it’s fine. The theme installs, and if you look at it from as an outside user it shows up, but it gives me that error whenever I go to edit the theme. What do I do?