trouble opening session: can't locate audio files

[eddie v]

hello. i'm having trouble opening a session that i've been working on a while. i'm working in pro tools 5.1.3 in mac os 9. every time i've opened it i've gotten a window several times that says please locate audio files. the last time i opened the session less than 10 files couldn't be located, i found most of them and had to recreate a couple. whenever i've had to locate files like this they have never been in the session's audio files folder but instead are in the folder i imported them into pro tools from (i'm working on editing sound fx for a film). what i've been doing is to locate the file in it's original folder and then drag and drop a copy of the file into the session's audio files folder so that that audio file won't be a problem in the future. i thought that the problem was behind me. i'm trying to open the session right now and have been locating audio files for over 45 minutes (i lost count how many) and i have no idea how many more i'll be locating. none of the files that pro tools can't find are the same as the files that were missing the last time i opened the session. so i'm a bit confused since the files that are not in the session's audio files today are ones that have been in the session's audio files folder the last 15 times i opened the session. what am i doing wrong and how can i fix this? thanks for your help.