Thanks for posting your psd file. I opened it and found a couple of surprising things.
The first can be seen in the attached image: There is no pink cast anywhere to be seen, and the background for the text is transparent, not a solid color. This tells me that the file is fine up to the point at which you flatten it.
However, like you, when I flatten your file, I get a light pink background. However, you will notice that if you place the eyedropper tool over the pink background, it reads 255,255,255, ie, what should be pure white.
This is a dead giveaway. The only way PS will display 255,255,255 as anything other than pure white is if the profile for the color space is telling it to do so. My next step was to inspect the color profile: Yup, it is not a color space profile, but a device profile (see 2nd attached image).
To demonstrate that this is exactly the problem, before flattening, I went to edit / assign profile and just arbitrarily assigned sRGB to this image. Now, when I flatten it, the 255,255,255 background turns pure white, exactly as expected.
Unfortunately, it's easy to confuse (input and output) device color profiles with color space profiles, and you managed to do this. Both types of files end in *.icm and are formatted identically.
If you are running your scanner from either software that came with it, or 3rd party scanner control software, e.g., Hamrick's VueScan, SilverFast, etc. the software should put out files in one of the standard color spaces, eg, sRGB, AdobeRGB, ProPhotoRGB, or possibly one of the many CMYK variants. Under no circumstances should it put out a file with the SF_T (Artix ArtixScan 1800f) embedded color profile. If it's doing this, it is set up incorrectly. Unfortunately, not knowing what scanning software you are using, I can't help you further.
HTH,
Tom M
