HELP, my new iMac keep getting disconnected when going into sleep mode

Hi guys, finally got my imac but it keeps disconnecting from wifi whenever it goes into sleep mode after inactivity. Not sure if this is a bug or expected behavior, either case is there a way to prevent wifi from disconnected?

The reason is I still want to be visible online in aim while away/inactive, so my friends can continue to send me messages and when i come back i can see it. However as it is now, my wifi gets disconnected so aim goes offline too.

I have latest imac mountain lion connected via wifi to airport express router.

Any help will be appreciated.

Chupa Chupa said:

If you don't want WiFi to go to sleep you go to energy saver and set computer to never sleep, hard drive to sleep when possible, and monitor to sleep at the interval you want.

You can also use power nap which is almost the same thing.

Click to expand...

i did exactly that, but the display never goes to sleep... i set computer to never and display to 10 mins, but it doesnt shut off even after 1 hr, the screensaver does come on after its timer but the screen never shuts off.

also all of sudden my imac doesnt have sound anymore, after half hr of checking everything it turns out the output source somehow switched to my airport base station (my airport router). Also trying to remove icon from the launch bar at bottom of screen doesnt seem to do anything, only after reboot it would do it..then when i try to remove another icon it wont work again..have to do another reboot..

i have no idea what's going on with this mac, if this is the most advanced os in the world as it claims..... missing windows already.