Originally Posted by Rearview
What browser do you use?
If the browser switches to high contrast then colors and backgrounds of websites also change. This is the case for IE and Firefox. Chrome seems to ask for HC extras but if you ignore them, you can still enjoy the sites in their original color even if you're on high contrast for the rest. Disabling HC in other browsers still needs to be investigated, if possible or not.
Check the full answer in your thread here.
I'm afraid those are some of the drawbacks of high contrast currently.
To narrow it down:
HC themes display issues
The image issue on the yahoo site happens here as well but not on Chrome, not saying that Chrome is better but because it can be fooled in displaying the site normally when still in high contrast. if some things still fail to display properly than its most likely because Windows renders things differently when high contrast is enabled.