I'm pretty sure the screen calibration isn;t the issue, as the evidence used with the screen capture cleary shows that in NX the image looks vastly different than it does in Windows Explorer.

Colour space is definitely in sRGB mode as shown in the lower left corner of the image in NX.

Some settings to check in NX Paul:

In the preferences settings (Edit->Preferences) check the settings enabled in the colour management tab.

In the 'Default RGB colour space' area makes use it's set to sRGB(which it most likely is anyhow), and check the tick to be 100% sure that the embedded profile isn't saved to the file.
it probably won't make any difference anyhow, as I think from memory you've set the camera to sRGB anyhow.
I think you'll probably see the option for Nikon sRGB 4.0.0.3001 or something like that.

I suppose you can only try different software to browse through your images too.
Try FSViewer faststone's image viewer.
It's a great image viewer, and reproduces Nikons NEF files faithfully(even all the in camera enhancements are rendered pretty much spot on.
Much faster as a browser than either Capture or ViewNX, but never edit or save any NEF files with it, as the quality is best described as atrocious!
It's fine for editing and saving jpgs tho.

As for the issue of uploading the images and having them displayed as you describe!!??

that is so totally weird.

just for testing puposes:

upload this particular image directly to AP as an attachment and let see how it compares to the screen grab you posted. At 450Kb you'll get a failed upload error, so resize it below 250Kb's. I find that at 900pix wide a quality setting of 60-70% should give you approx 100-200kb's for this particular image, so that should get your image onto AP as an attachment.

Could it be an issue with PB?

and to be sure!!
the image currently displayed in the CaptureNX window looks the same in both LR and PS??
.... so Windows Explorer is displaying the image 'wrong'?

and I highly recommend that FSViewer program too... I'm sure you'll like it.