Blending options not saving in multi-layer CMYK

hello, I hope someone can help with this strange problem that recently came up with one file:

Problem: -

The Blending options in a saved multi layer CMYK have altered themselves when reopening the photoshop CS document -

- When opening in any way (file Browser or other) -
- File thumbnail pic is displayed correctly -
- Opened file does not resemble the thumbnail -
- Color &/or Gradient overlay blend modes have reset themselves - (1
layer specifically)
- Use of other blending options unknown in the original saved document

- File contains imported Illustrator CS images & text - those blending
options have not varied based on the thumbnail pic


Any help would be appreciated! Thanks