Certain smell from bread after baking... Help!
After I have baked my bread, the smell of the bread (the inside) smells off... like sour.
I have made this bread before and it did not have the same smell, and it seems to be my yeast or flour.
i have a can of instant dried yeast (the one that looks like grains), I've opened it and it has a plastic cap, and I've closed it (obviously xD) and left it in a storage container under my table. Maybe I'm supposed to refridgerate it?
My flour is in a large container, with a cap (I had bought flour that was inside this container, and reused the container). I bought new flour for the below recipe (I made it twice), I'm not sure if the time I used the new flour if it had the smell or not.
Also, what is the difference between the paste/liquid yeast and the grainy yeast?
What brand of flour is "the best" or most recommended for soft breads (fluffy mm..)/breads that aren't dense.
Should I refridgerate my dry yeast (grainy one)?
the recipe i have used is : http://daddymommyloveraphael.blogspot.com/2009/05/japanese-butter-roll.html 
Also, I'm looking for an online friend / group of people that I can talk about baking to, preferably a beginner like me so that we can discuss new techniques, problems, solutions etc. :) maybe around my age (16) but doesn't matter so we can talk about times we make bread and how it may affect it etc. etc. but if you have the time to be on MSN or skype or something to talk about bread, please tell me so I can talk to people about bread!
Thanks in advance!