I get that every so often on my iPad (and iPhone) due to it throwing up the nag screen suggesting I try out Tapatalk. That nag screen fails to load correctly, leaving a blank page. Presumably the nag screen sets a cookie to say that I've been nagged even if it fails to display correctly, because when I navigate back to the main forum page everything then loads correctly, and continues to do so until the next time it decides I'm due for the Tapatalk nag again. I thought it could be the content-blocker I have installed causing it but haven't bothered investigating further.