I followed instructions that I came across on the internet to reinstall mac os x as I just got an iMac second hand. Was not given the option to 'Erase and install' and instead followed through the install and now things are not working properly. I noted down that it was OS X 10.1.5 now it is OS X 10.1.2. When I start up it only shows the display and the time in the top right corner. Will not display dock or finder. Please help! What can I do to fix this?