Dell :: Intermittent Wi-Fi Connection On New Inspiron 1506 Desktop

I have a Dell Inspiron desktop with Dell Wireless 1506 802.11b/g/n  card.  This PC is fairly new - purchased in October 2012.  Most of the time the wireless connection is fine, although the signal is weaker than it should be (about 2 bars).  Occasionally however the wireless signal drops to one bar or less, or is completely lost.  The result is loss of internet connection.  Restarting the PC will often restore the connection, although the signal level remains low.  This is very surprising as other 802.11b/g laptops and PCs, sitting on the same desk in the same room, will show a strong wireless signal of 4-5 bars.  I have measured the wireless network strength in that room using a laptop with inSSIDer and it seems just fine.  So I don't believe the problem is in the wifi signal strength.

The wireless access point is a Motorola surfboard b/g cable modem that is located about 25 feet from the Dell PC.  That cable modem is reporting excellent signal levels on the coaxial cable to the street, so the problem is not in the access point.  Connection speed when tested from other PCs/laptops on that network is just fine.

I am wondering if there is some sort of intermittent hardware problem in the Dell wireless adapter that might be causing this problem.  Or some sort of software conflict.