Pre8 won't link to/recognize files in Media tab of Organizer - please help

Question

Today I opened a project that I have been working on and it would not link to some or all of the files that have previously loaded successfully on numerous occasions. The project asked me to locate the files, and when I did, it said they could not be linked because they'd been created with one audio track and now had two. However, these were the exact same files that I've been working with, and have not changed them at all. When I did open the project (it was unrendered even though it had been previously rendered) the files were still in the sceneline and timeline and in the project section of the organizer tab, and appear to work in the movie, but do not show up visibly in the media section, where I just get icons but can't see the image.
This appears to be a problem with my program, because I opened older projects and even created a new one to test with, and same problem with loadng media. It will load, but won't recognize, and when I try to drag into the project,it opens a dialog box asking where the file is, but won't take it.
The only thing that I did immediately preceding this was last night, I tried to load an itunes mp4 audio file into the project, but it wouldn't take because it said the file type was not supported or the codec was wrong.
Please help with this. Could the program be corrupted? If so, how can I fix and not lose the projects I have made?
Thanks, Michael

Answer 1

Going back some years, I tried using USB externals for editing to/from, but found two problems:
1.) frequent read/write errors, usually delayed write failures. Many others were having the same problems.
2.) the speed was so horribly slow.
I then went with FW-400, and got no read/write errors, but the speed, though faster, was still too slow for me. When FW-800 came out, I experimented with these, and have been using them ever since. Now, eSATA would be even quicker.
I wonder if you suffered from some errors on the USB drive. I'd first use G-Spot, a free utility, to check the audio in your files, to see how many channels are shown there. If you find that the files are now showing a single channel, instead of two, you might be able to convert the files with a program like Prism, or DigitalMedia Converter, to 2-channel. You'd want to Move your source files to another folder, and then convert to the same file names back in your source folder.
One tip on using externals: in your OS, you can set your drive letters. These will always be assigned the same, based on the drive's I.D., so that F:\ is always F:\, and G:\ is always G:\, regardless of what else is plugged in, and the order they are turned on. This will keep PrE from asking where is file xxxx.avi, etc.
Good luck,
Hunt