As I mentioned on this trip I took a lot of pictures and had to reuse some of my cards. All cards were backed up from the CF cards to a NEXTO eXtreme (ND2700) 500GM memory storage device. At the end of the trip, those files were then imported into Lightroom4 and the issue was then discovered.
Since I had renamed the files on import, I decided to re-import them into a Test catalog for lightroom4 to see if the bad images were grouped close enough together that they could have been taken with one "bad" card. Had I discovered a bad card, I then would have determined the file number through lightroom4 and then manually checked each card to find the bad CF card.
When I re-imported the files from the NEXTO device into a new catalog in lightroom4, all of the images imported perfectly with no exceptions! I was able to find corrupted pictures in the first import and match them to non corrupted pictures in the 2nd import.
This leads me to the following conclusions; 1. The camera shutter is working fine. 2. The CF cards are all working fine. 3. The NEXTO device itself is working fine during its CF import process,
BUT; 4. Based on comments people have left, there may be a problem with the cable used between the NEXTO device and my computer. 5. There could we an issue with Lightroom4.
Since I have never had this issue with Lightroom before, to me the logical cause then seems to be the interface cable or some issue with the NEXTO communicating with the PC.
Thanks to everyone for their help on this issue. If anyone disagrees with my logic or conclusions please let me know.