problems logging in with remote desktop

I am using windows 7 ultimate on my desktop and laptop. I am trying to connect to my desktop. On my desktop I have created a credential. the name of my laptop is laptop. To make things simple lets say I put user name abc and password 123. From my laptop I put in abc for user and 123 for password I can connect to the desktop but it says invalid user name or password. I have tried creating different user names and passwords on the desktop fot the laptop. What am I doing wrong? Please help. I do not understand why this is so difficult. Its problably not but the help section in windows 7 does not give enough information. Please help. Thank you.

I don't know what I did but it works now. Now I have another problem. I have an external hard drive that I have been sharing. It shows on my network on my laptop but says I do not have permission to acess it. When I go to the main computer I have shared enabled with everyone. I used to be able to view the contents of the hd but not now