Where are these media files located? Are they on your C drive, a second hard drive or an external drive?
They're on an external drive connected via usb. and i did, before this happened, have a second external hooked up, so i thought maybe the drive letter for the one with the files had changed, from f to h, b/c a couple of times the program was asking for files on f: But then I changed it back from h to f and it didn't fix it.
Ok, just tried it again with the drive letter changed and it seems to have worked this time.
When I updated the de-linked files in the organizer it found them again. Don't know why this happened.
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.