Here's a problem I got today.  Microsoft ISA Server 2004 Enterprise Edition running on Windows 2003 with SP1 and all latest hotfixes.  I sporadically lose connectivity to the box internally for TS/RDP management from trusted adminnistration stations.  It appears to restore access after a reboot.  I've also had low memory complaints from the ISA Service.

This appears to have solved this problem, which is now looking like its unrelated to the low memory condition:

Event Type: Error
Event Source: TermService
Event Category: None
Event ID: 1036
Date:  24.07.2005
Time:  18:57:44
User:  N/A
Computer: Servername
Description:
Terminal Server session creation failed. The relevant status code was 0x2740.

Solution: http://support.microsoft.com/default.aspx?scid=kb;en-us;555382

To resolve the problem make sure that the correct network adapter is bound to RDP-TCP connection. To do this, follow these steps:
1. On the server, logon to the server locally (not using Remote Desktop/Terminal Client).
2. Click Start, Run, type "tscc.msc /s" (without qutation marks and click OK.
3. In the Terminal Services Configuration snap-in double-click Connections, then RDP-Tcp in the right pane.
4. Click the Network Adapter tab, select the correct network adapter and click OK.
5. Make sure that you can establish an RDP connection to the server.