That's an odd one. It sounds like the file is damaged. Can you open it in ArtRage?
If you can open it in ArtRage, you could recover data by exporting individual layers as PNGs ( right click the layer, choose 'Export layer' from the menu ), then creating a new file in Photoshop, opening the PNGs and using them to recreate the layers.
Also, if your PSD is smaller than 10mb you could email it to me at email@example.com and we can see if we can find out anything from it here. If it's larger and you want to get it to me, let me know and I'll send you some ftp details.