If it's wireless, then it's susseptible to radio interference. We've seen microwave ovens, other cordless phones, and even some cell phones cause interference with our wireless access points / routers. One thing you should do is a site survey, looking for other radio signals that might cause you problems. If there are other Wi/Fi signals causing you problems, you should try to set yours up to use a channel as far from those other Wi/Fi signals as possible (i.e. if they are using channel 1, try to set yours to channel 6 or channel 11).
Also, make sure the firmware is fully up to date on there. We've seen problems with outdated firmware before as well.
Good luck,