while I was uploading my files from my CF card to my computer the screen went blank. I checked the card and it was also blank. I bought a recovery program from the net for $70. it recovered some old files but not the ones from that day.
So I went to the Sandisk site and bought it's Recovery Pro program for $39 and it worked! retrieved my files. tested that card the next day after formatting and it was fine. but the next day it went blank again.
I called Sandisk and discovered the card had a 3-year unconditional warranty. the rep said they would warranty the card even without proof of purchase but it might take longer. With proof of purchase and pictures of both sides of the card Sandisk emailed me a paid return label the next day.
so cards do fail. even the best. I have always only used SanDisk, a local company, and I will continue to. great no-hassle service!