I'm not sure if these two are related or not (and too busy to read through the old posts again at the moment), but you might want to take a look at this thread where the user was complaining of a "too dark" screen to see if it may be the same problem. Even if it isn't the same issue, some of the suggestions made there may apply to you. Have you tried just adjusting the monitor? Many monitors retain their verious settings for each combination of resolution and scan rate, and allow you to have different monitor settings for each mode that you use, so it is not out of the wuerstion that Knoppix just booted into a resolution and scan rate that happen to be set to look washed out on your monitor. (Of course, that's only a theory and it could well be something else.)