Any smokers in the house?
The lenses could be dirty, from airborne contaminants, smoke, dust, etc... Try a optical drive cleaning disc - you can get them almost anywhere.
example from Amazon: http://www.amazon.com/Allsop-23321-Carbon-Edge-CD-Drive-Cleaner/dp/B00000J1QM/ref=sr_1_1?ie=UTF8&s=miscellaneous&qid=1261963461&sr=8-1
You could also try different brand and type media