I have recently been bitten by the Color Management piece of Photoshop. I have been developing a site for a customer (Genesis Family Child Care) and everything looked fine on my Mac. However, to test cross-site compatibility, I opened my simple page in a Windows 7 VM, and up popped two lines, top and bottom, where I had inserted a .png file to complete a transfer from one color to the next. What???
So I did a few searches online, some of which suggested that I fade to white to avoid problems, or use web-safe colors (where’s the fun in that?). Then, I read a post on a site which mentioned that color management might be the problem. I opened the .png file in Photoshop, went to the “Edit” menu, clicked “Assign Profile”, and checked a box in the resulting dialog which stated “Don’t Color Manage This Document”. That. fixed. everything. Thank you, internets!