Compatibility 5.5 vs 6

I've been working on a .PSD for class. I began the project on a version 6.0 (PC), finished up... saved it as a PSD, then took it home to my v. 5.5. Next thing I know, I get a message when I loaded my image: "Could not open the document because the file is not compatible with this version of Photoshop." I just assume it was the version differences. So I took it to class the next day, tried to load in on a MAC v. 6.0(1) and I got the same error message. My file does not load at all!

Anyone have any ideas? Is there a v. 6.0 AND a v. 6.01? The only thing I can think of is 1) When I saved the file the first time, I perhaps didn't save it as the correct version (this is really one of my first experiences with photoshop, so bear with me)? 2) If that IS the case, then maybe I can go back on the 6.0 machine and save it correctly.

Thank you.

It pretty much has got to be a problem with how you saved it initially... I take files from a version 6 (windows) to a version 4 (Mac) .....Daily

Go back to that machine that you saved it from, chances are....IT wont open the file either.

But how many different PSD file versions are there to save as? You would think version 6.0 could load any of them! I just cannot imagine Photoshop not being able to read its OWN file format! That's kinda silly. When I saved the file, I dont recall there being many different options and check-boxes. What could've possibly went wrong? It's not a corrupted ZIP disk, because every other image on the disk loads (of course, the important image is the one that doesn't load).

Photoshop can open older/newer formats of .PSDs. Though if something is amiss, it will tell you there are errors, but still open up the file. It will just most likely rasterize or layer-lock anything it doesn't recognize from the version you are using.

It does sound like whatever happened when you first saved the file, something happened to it.