Cure Poision cures the icon, but sometimes still poisioned
 

I notice as a Human Pally I cast cure poision and it appears to cure the poision and the pic of the poision disapears, but I am still poisioned and my health goes down and it later says the poision has run its course much later after I cured it.

That's a graphics bug. It removes the icon whether or not it cures the poison. Cast the spell until you've removed enough poison counters that you get a "you have cured your target" message.

/bump i am having this problem as well!