Error when saving product: “Duplicate website group price customer group.”

Question

I get this error message when I try to save a product, which reads to me like a random sequence of nouns (the German translation is even weirder but I am used to that...)

Traced it down to this method in Mage_Catalog_Model_Product_Attribute_Backend_Groupprice:

/**
 * Error message when duplicates
 *
 * @return string
 */
protected function _getDuplicateErrorMessage()
{
    return Mage::helper('catalog')->__('Duplicate website group price customer group.');
}

The weird thing is, the article does not contain any group price. And even if i don't change anything, the message appears. What could possibly be broken here?

Update: Actually there is a group price definition, I did not notice it because it had been moved to the "general" tab:

Answer 1

Found it... removing the website specific definition solved it. Apparently you cannot combine a customer group price for "All Websites" with customer group prices for specific websites.