The Terminal Service RemoteApp (TS RemoteApp) feature is new with Windows Server 2008 and Windows Server 2008 R2. When Microsoft Dynamics GP was configured with the TS RemoteApp feature, certain pop-up windows would not appear and Microsoft Dynamics GP would appear to “hang” or “lock up”. Because of this issue, Microsoft Dynamics GP 10.0 and Microsoft Dynamics GP 2010 were not supported with the TS RemoteApp feature.
Install this hotfix from Microsoft on your Windows Server 2008 or 2008 R2 to correct this issue. Hotfix for Terminal Server issue