Screen has gone yellow

Using CDR X6, and today the screen has gone yellow, ONLY in CDR, all other programs screen is normal, where you would expect white, screen is white.  In CDR, the entire work area is tinged a dirty yellow.  The pages I'm working on as well as outside that page, yesterday it was white, today yellow.  I've restarted CDR & windows.  Using Win7.  When printing, the white background is white, so this appears to be a screen issue only in CDR.  Any ideas?