I once had a problem with my Video-DAC which caused the screen to seem
blueish in hue. It wasn't a gun on the CRT either.
If you selected Tools->ResetWB and it corrected itself then maybe you
are running AWeb on the Workbench screen and the animated logo is
sucking out your palette pens.
Go into it's MUI prefs and into the Commander. Make a new screen for
AWeb so it's off Workbench and then get an utility like FullPalette to
lock your all essential pens on Workbench.
http://ftp.uni-paderborn.de/pub/aminet/util/wb/FullPalette22.lhaMagicWB icon package tends to mess with the entire palette too, but i
suspect something on your Workbench is doing it.
I remember before getting FullPalette half my icons would be blue and
pink due to the MagicWB pallete allocation of the first 4 and last 4
colours.
:-D