Network Computer not accessible after changing password

Hello - I am on a network that contains both XP and Windows 7 computers. The problem at hand is on a Windows 7 computer (Computer 9). The XP computer is Computer 4. I succeeded in accessing Computer 4 from Computer 9 by typing my Computer 4 credentials into a window that popped up on Computer 9 the first time that I attempted to access Computer 4 from Computer 9. After that, the password on Computer 4 was changed. Now, when I try to access Computer 4 from Computer 9, I receive the following message:

"Windows cannot access \\COMPUTER 4
You do not have permission to access \\COMPUTER-4. Contact your network administrator to request access."

Can anyone please tell me how to access the pop-up window on Computer 9 that will let me type in the new Computer 4 password? Thank you.

I'm more or less having the same issue right now.

removing/editing the credentials should solve the problem.

open a start orb
Type in credentials
Select Credential Manager
Under Windows Credentials find The computer your connecting to, and click on the down arrow. From there you can either edit the credentials for the XP machine or just remove them and then reenter them when you connect again.