I'm attempting to run this game on Windows 7 64-bit with following specs:
AMD Phenom II X4 955 Processor 3.2GHz
8GB RAM
Nvidia GeForce 430GT

While I'm pretty certain RAM has nothing to do with this, I'm concerned about my graphics card and processor.
I had the same problem with Sea Dogs - both games have freakishly purple menus and weird artifacts (not displaying any kinds of letters/fonts). It makes them unplayable.

BTW, my Robin Hood isn't from GOG, it's from "eXtra Klasyka" series - from about 2004, I believe (that series was conducted by none other than CD Projekt-- I mean, CDP).

So, any way to solve this?

I played in this game on Linux by wine-emulator and have some artifacts in menu/map/action panel. I think it depend from some features game engine. Desperado - other game this studio have similar problems. Here is example such artifacts: https//appdb.winehq.org/appimage.php?iId=15972. I think it's problem in your version of game and gog-version doesn't have this bug. But I'm not sure on 100% because can't check gog-version in windows-system.

I'm having a very similar problem I just posted in the forum about. Mine isn't purple but otherwise sounds the same as yours, everything is ultra-blurry for me and the fonts are unreadable. If I move the mouse over the buttons on the right the words become temporarily partly visible then quickly blur again with some kind of special effect. It's impossible to really start a game with this.


UPDATE: I found a solution to my problem that seems to work for this game and also for Alien Nations so I presume it'll work for other games too. While I have AMD video hardware it is possible something similar could occur on nVidia as well and they probably have a very similar setting in their driver control panel, so if anyone experiences problems of this nature it is worth trying the solution I found, which is to disable "Morphological Filtering" in a custom application profile in the video driver for the game in question. Details in the link above.