Some more updates...
After running the router for a day in "G only" mode without any wireless restarts, I changed it back to "N and G mode" and the wireless restarts started happening again.
I then changed the 2.4GHz channel from the 11 to channel 13 that I was using a few months back and since the last 3 days there have been NO wireless restarts..
BUT I noticed when I download at full speed from newsgroups (between 5.9 to 6 MB) the router locks suddenly and I lose connectivity to the internet...
Slowly my http browsing on a wired connection returns to normal but on the wireless connections, I get the timeout errors and the download speeds on my wired computer almost grind to a halt..
A quick reboot of the router and I am back to normal again...