Jeff, I’m not sure you understood Dave’s suggestion. The problem is not the openfiledialog statement, it’s the openfile statement. You should replace that with the opentextfile statement.
if file = "" stop endif
OpenTextFile "+"+folderpath(folder) + file
You mentioned that the user “downloaded a .csv file”, but did they give the downloaded file a name that ends with .csv? I’m guessing they didn’t, and that’s why openfile could not recognize what sort of file it was. The openfile statement tries to figure out what kind of file it is based on the extension, if there is no extension, or an extension it doesn’t know about, it won’t work. (It can also try to figure out the type of file from the type/creator code, but web browsers don’t support that old MacOS technology.)
The opentextfile statement does not try to figure out what kind of file it is. It simply assumes that any file you pass to it is a text file.
Because of this ambiguity, I stopped using openfile a long time ago. If I want to open a database, I use opendatabase. If I want to open a text file, I use opentextfile. This wasn’t a problem back in the Mac OS 9 and earlier days, back when all files had type/creator codes. But OS X deprecated type/creator codes, so few apps use them any more. Instead we all really need to put extensions on every single file will create, otherwise programs won’t be able to figure out what’s in them. It’s really a move backwards by Apple, but it is in line with what DOS and UNIX do, so it does make it easier to move files from platform to platform.
A really unfortunate choice Apple made is to hide the file extension of files in the Finder by default. Whenever I first set up a new computer, one of the first things I do is change this preference so that file extensions are shown. Otherwise it’s a constant source of confusion. Unfortunately, few users follow this practice.