Hi View any user on here and then click on the "Posts" link on the profile.... it just shows some random selection of posts and not the posts by the user you just clicked...
I do see what looks like a coding error in the Groups. When displaying a person's Profile in a thread there, the link leading to their posts is different than in the Forums.
smess "Posts" link on Dev Group: https://umd.net/groups?forum_search_criteria[author_id]=18874&search_submitted=1
smess "Posts" link on Messy Forum: https://umd.net/forums?forum_search_criteria[author_id]=18874&search_submitted=1
The former yields erroneous results and looks like it may be a "typo". If it's something else you're experiencing, clearing cookies has worked for me on other things.
The forum / group searches will pull up whole threads that the user replied in, not just ones they initiated. So a bunch of the results will be threads started by other people.
Whether the URL starts with /groups or /forums shouldn't matter at all because the search always hits all groups and forums. The results should be identical either way, but let me know if you see any different.