Out of curiosity, what do you expect people to offer you after an overly terse description like that?
- Exactly how are you saving the files and how are you trying to open them (understanding that there isn't just one way)?
- Have you tried opening your files on another system to isolate whether it's a problem with saving or with opening?
- Does it happen with every file or is it intermittent? If the latter, does it happen with big and small files?
- Do any of the diagnostic or error logging facilities on your system show anything's wrong with it? Are you seeing problems in any other applications?
What version of Photoshop?
And are you sure you're not just saving a different format and putting .psd on the end?
Also if you should get an error message could you let us know what exactly it states?