Please, a friend of mine had done successive installations of Bit Defender on top of older installations from the CD ROMs she had purchased, culminating in the latest installation of BD 2013. When she had problems opening BD from the desktop icon (which tried to open BD 2012), I deleted it for her and deleted the older BD files (labelled Bit Defender 2009, Bit Defender 2010 etc. in the Program Files folder in Vista.) Now her computer decided to "go wrong" and she had to do a hard reset. It then booted succesfully. She thinks it was an issue with BD which caused it to crash.
I would be grateful if someone would outline the simplest option to get Bit Defender 2013, and the PC, working properly again? Thanks in advance! :-)