XF 2.2 Question on a couple bugs

Hey all. Just curious if anyone knows what these could be

1. When scrolling through a thread, sometimes the entire screen will suddenly turn black. If you scroll back up it fixes itself, so it’s not a big deal but annoying.

2. When someone marks an entire forum as read, the logo will disappear. Again, it fixes itself usually after a few minutes, but it’s annoying.

Any ideas? Thanks everyone! My forum is www.theplatinumboard.com for reference.