Black circles at corner of some model elements ?

[db]

Hi... has anyone had an issue with small black circles appearing at the corners of some model elements ?

I've had this problem a few times but think I have just ignored it in the past, but it's annoying me now.  In my current project it is occurring at the corners of a structural foundation slab when viewed in section.  Screenshot attached.

I've tried changing various settings but can't seem to get rid of them.

Thanks

[db · Accepted solution]

Solved.... It was foundation projection lines being set thicker than cut lines.