Solution to stabilize my BEFW11S4 V4 wireless router

Updated July 2009: I upgraded the firmware of this router back to 1.52.02, and it's now working stably with WPA-PSK (TKIP) enabled.

1. I have been had a headache with my Linksys BEFW11S4 V4 wireless router. It couldn't work reliably when the wireless function is enabled and I'm not alone with its problem. Click here for others' experience of the problem.
   
2. The symptom of the problem is: Router locks up (doesn't respond to ping and web interface inaccessible) in a few hours after the wireless function is turned on. The only way to reset it is to unplug its power.
3. First I tried to disable UPNP in the router as suggested by some at the above link. But the problem is still there. I didn't disable UPNP on my networked computers though.
   
4. Solution: I downgraded the firmware of my BEFW11S4 V4 to 1.45.3 and since then everything worked fine. I think the only thing lost is WPA but I don't use it anyway. The 1.45.3 firmware can be downloaded at this address.