Game Mechanics: Mana regen stops

[Lovely]

I've noticed this since the first week of the server but I never bothered to post about it since it wasn't that much of a big deal. Anyway to the problem..

Frequently your mana regen just suddenly stops when you sit. For some reason it always seem to happen at the worst times like if you got a mob rooted and need mana fast. What happens exactly is that your mana/hp regen goes up and then straight back down to the original number. Sometimes it will happen over 10 server ticks in a row..