Are you using LANDesk Powermanagement to put these machines to sleep? Does this occur on every kind of machine or just on laptops or machines with a certain type of video card, etc? Have you tried updating to the latest video driver on one of the machines to see if its just a direct 3d thing?
I have observed this on laptops and desktops of various models. It doesn't seem to matter what video chipset or driver is involved. It appears that as long as the video card/monitor are in standby mode while the rest of computer is running, I can't get any video through ISSCNTR until the local monitor is displaying an image.
I am using Verismic PowerManager, but the problem has been observed on computers without Verismic (not installed on any laptop) that wake up but leave the video in suspend.
I still observe this on LD9 SP2 with the latest published MCP for Remote Control patch installed:
1 - Right-click a computer in the Console
2 - Wake it up
3 - The device wakes up, leaving the monitor asleep
4 - No video in ISSCNTR
5 - Move the mouse on the computer to wake up the monitor
6 - Video appears in ISSCNTR