Hope you come up with a fix. I've been having the same problem for months. If I figure it out I'll post. Its horrible. I've had it drop during college tests which resulted in temporary failures, and instructor won't give any more retakes due to the problem.
Well I think the problem is solved finally. I upgraded the firmware version of my DIR 600M router from 3.01 to 3.05. There have been no drops for 2 days now. Thank you everyone for all your help. Cheers!