"Invalid login. Please try again." appears during an attempt to initiate a Remote Control session to a managed client computer with the pcAnywhere plug-in installed.
One cause of this error is changing the Primary group of the user to "Domain Admins" within Active Directory Users and Computers, under the user properties on the "Member Of" tab.
The default value of a user's Primary group in Active Directory is "Domain Users". According to this article by Microsoft, there are only two reasons why changing the Primary group may be necessary:
using Services for Macintosh or
The article also states that otherwise, there is no need to change the Primary group. If you experience this issue and your domain user accounts have been modified from the default Primary group, then Symantec recommends that you revert the change back to the default value of "Domain Users". If you have a legitimate need to modify the Primary group based on the reasons above, please contact Symantec Technical Support.
This has been observed on host computers running Windows 2003 and XP, but not Vista.
Screen shot of Primary group set in Active Directory as "Domain Users"