Anyway i tried some rough dirty code,hope some expert will you give clean solution.
Code:
txt=browser("browser").page("page").weblist("select").getroproperty("innerhtml")
arr=split(txt,"</OPTION>")
set disabled_items=createobject("system.collections.arraylist")
for each i in arr
if instr(1,i,"disabled")<>0 then
disabled_items.add mid(i,instr(1,i,">")+1,len(i))
end if
next
ai=browser("browser").page("page").weblist("select").getroproperty("all items")
set all_items=createobject("system.collections.arraylist")
ar=split(ai,";")
for each i in ar
all_items.add i
next
for each i in disabled_items
all_items.remove (i)
next
cnt = all_items.count
randomize
myvalue = int(cnt * rnd)
browser("browser").page("page").weblist("select").select(all_items(myvalue))
set disabled_items=nothing
set all_items=nothing