Can't see masteries descriptions?

When I hover over a mastery skill with my mouse it gives me no description of what the mastery skill does. Also whenever I launch league of legends and try logging on there will usually be an error one or two times before I can actually launch league of legends causing the LoL client to automatically close.

I'm going to uninstall league of legends and then reinstall it to see if that helps at all, but in the meantime I thought I would throw the bug out there to the development/bug team.

To further help understand what may have caused the bug it began after the patch 5.10 and patch 5.90.