A quick fix is comment line 691 in /app/code/core/Mage/Adminhtml/controllers/Catalog/ProductController.php. Like this:
//Mage::getModel('catalogrule/rule')->applyAllRulesToProduct($productId);
not fully test. But that line is not existed in v!.4.1.1, added in v1.5.0.1.
ref http://www.magentocommerce.com/boards/viewthread/221229/