I'm working with CS2. I always save files as TIFs -- occasionally, when I try to re-open a particular one, Photoshop says it can't open it because it is the wrong kind of file and when I check the file, it says "Image type: file", rather than "Image type: TIF"
I can correct the problem by opening the image in Paint Shop Pro and saving it as a TIF and then going back to Photoshop -- where it is still a TIF.
What's up with this and how do I get it to save my files as TIFs each time? I work with large files, but there doesn't seem to be a correlation between file size and when this happens.
Thanks for you help.

When you try to open these files with Photoshop, are they coming from a CD or DVD?

I'm working with CS2. I always save files as TIFs -- occasionally, when I try to re-open a particular one, Photoshop says it can't open it because it is the wrong kind of file and when I check the file, it says "Image type: file", rather than "Image type: TIF"
I can correct the problem by opening the image in Paint Shop Pro and saving it as a TIF and then going back to Photoshop -- where it is still a TIF.
What's up with this and how do I get it to save my files as TIFs each time? I work with large files, but there doesn't seem to be a correlation between file size and when this happens.
Thanks for you help.

The files are saved to my hard drive and the time between saving them and trying to re-open them varies between less than a minute to a day or two. If I go to "recent files" I can open them, but not if I go to the hard drive. Also, the thumbnail doesn't display in the file folder for these files, although it does for files correctly saved as TIFs.

I appreciate your help.

Most probably, your files lose their extensions (for I can't imagine what reason).
Pull down "File > Open As" and in the dialog box choose "Open As: TIFF"

Or just reveal the files with a regular file manager (like "Total Commander") and type ".tif" at the end.

Thanks! That was exactly the problem. I must have removed the extension without knowing it when I saved a version with a new name.