The first thing i would do is check the manufacturers site to see if there is a firmware update. If a lot of people are experiencing the same thing it could be something they fixed with an update.
Also what frequency are you running b/g = 2.4, n=5.0. Lastly what channel are you running.
Could there be interference between channels or frequency? (neighbors access points is running at the same channel, or cordless phones are interfering with the frequency)