I just upgraded to 9.0SP2 recently.
I got the exacty same problem.
Some devices appears as if they were on but in fact they are not but because console thinks they are up I cant even wake them up because option wake up is grayed out. That realy sucks.
Until LANDesk fix this there isnt a great deal you can do. However, on the waking up of devices you should try our Wake-On-WAN plugin. This will give you right-click wake-up capability (the free bit) whether LANDesk believes the machine is online or not.
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