Very Weird problem with PSD files.

My problem is this: whenever I save my work as .PSD file, it saves and instead of getting the typical icon (the blue one with PS written on it), it is just an icon depicting a blank paper sheet. The first time I discovered the files were corrupted was when I tried opening them on a different PC, and it said the format wasn't compatible. Weird thing is, in my PC they do open. I tried adding the .psd extension to every file, but it didn't change anything. An what's even stranger is that when I see the properties of the files, it says they are a "photoshop.image.9" or "photoshop.image.12" file. That must be why I can´t open them in other computers, but thing is...: why does my PS save them like that, even though I save them just as .PSD? is it my computer that's misconfigured?

If anyone could help, it would be appreciated, I alrerady tried asking my teachers at college, but none of them has been able of giving me an answer.

Not sure why you're getting two different property messages : "Adobe Photoshop Image 12" signifies the version of PS, ie 12 is CS5, 9 would be CS2 i believe.
the obvious stuff first : does this other PC actually have Photoshop on, and if so, is it the same version as you've got?

adding extensions : this is pointless. if your machine shows, for example a JPEG image name as, say, "Image", then it means that under your File & Folder options, in Windows, you've ticked to hide known extensions. the real full name would be "Image.JPG" - if you add the PSD, you're adding to the name, so it's still a JPEG but now actually called "Image.psd.jpg" : if you want to change an extention, you have to shwo the extensions and change THOSE.

what is the wording of the error message you get, does it say it's corrupt or such like, or is it just not recognising the format?

Well, I never said I added the PSD extention to JPG files...that's pretty stupid LOL. I added the extention to the actual PSD files I saved (which didn't work). Yeah, the other PC had photoshop (it was at my college, so every PC has to have every Adobe program). The version was CS5, the same one I have on my PC. I also tried opening the PSD files on the Mac PC's at are also there, but nothing.

The extension of the files I get when I save PSD files is Photoshop.Image.9, the other one, Image.12 was an experiment I made: I installed PS CS4 on another account on my PC to see if it was just a problem of CS5, but I got the blank sheet icon once again...

I really need the PSD files, since working on JPEG files is not really...handy.

Thanks for the answer, BTW