Going to Customize > Themes change to a random page.
it shows broken images on some of the themes, and when clicking some of them. It says, "Sorry, but you're not allowed to access the file you requested."
Just thought I would say something to prevent others from having the same issue :)
Just tried, and seems to work fine for me right now - but a few months back, when this topic was posted Getting some random blocks (https://www.simplemachines.org/community/index.php?topic=590750.0), I did see similar things happening for a while.
I made a server config change this morning and ran out of time to post, but I think it helped.
Sweet. I can access now. I clear cache and such, full nine. Thank you good sir.