Hey, you got a problem with blue? I happen to like blue, so don't go dissin'
one of my favorite colors, OK?
But seriously...
You don't say whether you have a CRT monitor or an LCD, but I'm going to
guess it's a CRT, because it would be extraordinarily unusual to have that
problem with an LCD.
Most probably, either your video cable (that connects your monitor to your
computer) or the monitor itself need replacing.
Restart your computer in Safe Mode. Still see blue? In that case, it's
definitely the monitor or the video cable. Power down your computer and
detach the video cable from both ends. While you have the video cable in
your hands. have a close look at the pins in the connectors -- they should
not be broken, bent or loose. If they, try a new video cable.
If the pins look fine, and you still see blue after carefully re-attaching
the video cable, it's time for a new monitor.