CGMiner and 5830's give my the BSOD and GPU hangs, DEAD threads
Try to lower GPU clock a little bit to let's say 900MHZ or stock, and also make sure that the memory clock is not lower than 300MHZ. After that try to keep an eye on the GPU temperatures as this may be the cause of the sudden BSOD. Also there is a intensity parameter, if you keep it as 9 then try to lower it to 7. My config for 5830 looks like this:

{
"pools" : [
    {
        "url" : "mint.bitminter.com:8332",
        "user" : "username_workername",
        "pass" : "worker_password"
    }
],
"intensity" : "9,9,9,9",
"gpu-engine" : "0-950,0-950,0-950,0-870",
"gpu-fan" : "0-85,0-85,0-85,0-85",
"gpu-memclock" : "300,300,300,300",
"gpu-powertune" : "20,20,20,20",
"temp-cutoff" : "95,95,95,95",
"temp-overheat" : "85,85,85,85",
"temp-target" : "80,75,75,80",

"algo" : "4way",
"auto-fan" : true,
"auto-gpu" : true,
"expiry" : "120",
"failover-only" : true,
"gpu-threads" : "2",
"log" : "5",
"queue" : "1",
"retry-pause" : "5",
"scan-time" : "60",
"temp-hysteresis" : "3",
"worksize" : "0",

"donation" : "0.00",
"shares" : "0",
"kernel-path" : "/usr/local/bin"
}


and works for over a year now :)