Should be able to access it in safe mode .To get to Safe mode, press the F8 key when Windows starts to boot. You have to do this BEFORE you see the first "Windows" screen. You can start tapping away as soon as I get by the BIOS startup screen or the manufacturer's splash screen. Experiment and you'll get it.
It sounds like the security permissions associated with the folder do not recognise your new persona so you will need to take ownership of the folder to access it. A guide to the process is available here...