Windows Remote Desktop

I can't log on to the remote computer

If you can see the logon screen of the remote computer but you can't log on, add yourself to the Remote Desktop Users Group or to any group with administrative rights on the remote computer (or ask the administrator of the remote computer to do this).

To add a user account to a group

1. Open Microsoft Management Console by clicking the Start button , typing mmc into the search box, and then pressing Enter.‌  If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
2. In the left pane, click Local Users and Groups.

   If you don't see Local Users and Groups

   If you don't see Local Users and Groups, it's probably because that snap-in hasn't been added to Microsoft Management Console. Follow these steps to install it:

   1. In Microsoft Management Console, click the File menu, and then click Add/Remove Snap-in.
   2. In the Add or Remove Snap-ins dialog box, click Local Users and Groups, and then click Add.
   3. In the Choose Target Machine dialog box, click Local computer, and then click Finish.
   4. Click OK.
3. Double-click the Groups folder.
4. Right-click the group you want to add the user account to, and then click Add to Group.
5. Click Add, and then type the name of the user account.
6. Click Check Names, and then click OK.

For More Detail

http://windows.microsoft.com/en-sg/windows7/why-can-t-i-connect-using-remote-desktop-connection