Had similar problem as others. The Nook charger has a special micro USB plug with extra connectors and a higher power output than most other micro USB chargers.
The solution is to NOT USE the B&N charger unless necessary as it appears only good for a few uses before the cord breaks. Do a search on USB Micro-B charger or USB Micro-B cable
You will find many options. The main difference is that the satandard USB Micro-B does not put out the power the Nook color needs to charge while it is running as it doesn't have the extra connectors for the extra power.
These lower output chargers will charge the Nook color if you first shut the Nook off then plug it into the charger. It will take longer too,
The BIG plus is these chargers can be had for less than $5 and the cords don't fail after a few uses.
Yes the B&N charger is SPECIAL and it will charge the Nook Color faster but as we are all learning they did a poor job of designing and manufacturing the special cable and gave it internal wires that appear to be too small for use as a plug that will be connected and disconnected more than a few times, and many of us are seeing premature failure.