Just a quick query - re. the measurements you left me for a standard loaf you made no mention of including any sugar. Did you just forget it or do you really not use any sugar to activate the yeast?
I would only add Suger to an enriched dough as a flavouring and a crumb softener. There should be enough natural sugar in the flout to generate the food for the yeast in fact when you start to produce enriched doughs you will find that high levals of sugar will act as a retardent.
If you do need to add a yeast food to the dough then I would add a malt extract (you can get it from the healthfood shops ) and just a half of a teaspoon to your 500grams of flour this will help with the development of the dough and enharnce the crust retention