Just curious but are you staying in Sonoma County right now? Where did you pick up the camera?
Redwoods are tough for exposure, the light is filtered through branches and there is usually a lot of dust in the air adding some haze and changing the color of the light often. Seems to me to be a white balance issue. I like the suggestion of putting the camera in live view and cycling through the WB settings to see how it changes.
Is it normal that when the batter is not in the camera then the view is a bit grainy???
I am in Sebastopol right now and I bought the camera in Best Buy in Santa Rosa I think.
Do I just cycle through the white balance aiming at anything?
When you do take more sample shots, take versions with the filter off as well.
What does not make sense is that the picture you posted has a purple tint.
Download a copy of ImageResizer.
This will help you avoid the route you took to sample the photo.
It all sounds very strange to me! (and in my view, never anything at all to do with a cheap UV filter).
By the way, if you live in the UK, are you sure you will get warranty cover (in the UK) for your US purchase? Also, dont forget to change the video out to PAL when you get home
Good Luck
Take comfort in the fact that Digital SLR cameras are amongst the most reliable electronic consumer products. I am not sure whether that warranty means you need to ship it back to the country of origin...hope not.
Didn't you look at the prices in Dixons at the airport? often I have found them to be cheaper than stores in the USA for such kit (unless you go to Costco!)
With regard to the filter, I don't want to open a whole new topic (and get blasted), but I have always bought quality filters to protect my glass.
I shop around and have purchased the Hoya HMC Pro1 filters (UV and Circ Polarising) in the past. For my recent purchase of a D90 I found some great deals on the new Hoya HD UV filters. This one one Amazon.co.uk for example.
As I said others will have a different view but that is my view!
You will also be able to find great value Nikon Batteries and the remote (all original -- if you are patient and watch the prices)
The D90 offers an amazing level of flexibility for the price, get out there and start taking pictures.