4
OK, that was quick. I just figured out what was going on.
I was having this same error message ("taking you back where you were") when I was trying to edit system and news templates. I just realized that at some point I cleared my browser cache (in Firefox, using "clear private data" and selecting only "cache"). I left cookies and authenticated sessions alone (so XOOPS wouldn't make me re-login), thinking I'd be OK. However, apparently this was the cause, because when I logged out of XOOPS and back in it quit giving me the "taking you back where you were" error. Apparently something in Xoops' session mechanism relies on cached items and not just session cookies. Definitely a problem for a developer to look at.