Check if the monitor cable is securely plugged into the slot. Also, make sure the RFI inhibitor (I dont know if thats what you call it), the thick round thing near the end of your monitor cable is all right. Tweak it around a bit and see if the bluish tint increases/reduces. If it does, then its usually a problem with the monitor cable and you would need to get it serviced. Also, degauss your monitor once (accessible from your monitor's menu) and check if that reduces/removes the tinge.