One common problem in X windows is that the screen colors can be abnormal if other X programs have already allocated all the colors. If the colors don't look right, try quitting colorful applications such as Netscape, clearing any complex images in the background, etc. so that Bochs has a chance to allocate the colors it needs.
If Bochs continues to have problems, or you want Bochs to have perfect colors without having to quit any other application, you can try turning on the private_colormap option in the configuration file. Using a private colormap causes the Bochs window to have its own set of 256 colors to work with. When the cursor is over the Bochs display, Bochs will look correct and other parts of the screen may change to very strange colors. When the cursor goes to any other window, the other windows will look correct and Bochs will have strange colors. A better solution, if your hardware can support it, is to run your X server with 24-bit or 32-bit color.