asterisk users - Oct 2005 - Callcenter and Softphone hanging

Hi,

I run a small inbound callcenter with 3 agents doing techsupport. The 
agents are logged in via softphone, using agentcallback login. Some 
times the agents PC running softphone hangs, and they reboot the PC. But 
* is not aware of this and tries to send calls to the PC, which gets 
rejected.

     -- outgoing agentcall, to agent '1009', on
'Local/1002@from-sip-c3fa,1'
     -- Executing Dial("Local/1002@from-sip-c3fa,2",
"SIP/1002") in new
stack
Oct  1 23:16:51 NOTICE[16907]: app_dial.c:777 dial_exec: Unable to 
create channel of type 'SIP'
   == Everyone is busy/congested at this time
     -- Called Agent/1009
     -- Timeout on Local/1002@from-sip-c3fa,2
   == CDR updated on Local/1002@from-sip-c3fa,2
     -- Executing Hangup("Local/1002@from-sip-c3fa,2", "")
in new stack

Is there any way to logoff an agent from the queue in such cases from 
the * prompt? Any better way to handle this issue?

raj