When I try to enter a nether portal I get this SEVERE errors:
http://pastebin.com/BUU8d8Tg

But it's strange because I will be teleported to nether though. Didn't try with End portals, may be the same issue.
CB: 1.2.3-R0.2-b2060
MultiVerse-Core: v2.4-b524
MultiVerse-Portals: v2.4-b538
Multiverse-NetherPortals: v2.4-b527

And sorry guys for forcing 1.2.3 update, I know you're working on it. Just wanted let you know

Just use a newer build of MV-Core and your problem will be fixed.