I did read the page you specified, hours ago earlier today. The part I see now that seems to pertain to the problem (just to leave a breadcrumb for anyone else having the same issue and is not ultra familiar with WordPress) is stated here:
----- It's important to guarantee permalinks lead to individual posts within your custom URI, so make sure to end a virtual site structure with either %post_id% or %postname% -----
P.S. I was having the same *symptoms* as the prior poster. The solution was different. Thank you for not "getting bored" and moving on. Although I would think that would not be a desirable quality in moderator of a helper forum :)
Resetting to default worked, yes.