I have found that if you do not remove all Remote Busy Lamp buttons (DSS/Busy Lamp), then when you go and switch from Hot Desk to regular user, you will get the fast blinking light on the phones. When you remove them first, then switch the phone from hot desk to standard, then everything will work fine. You will have to go back through and add all the DSS/Busy buttons back in.
Hope this helps. I have not tried a reboot of the switch to see if it would clear it.