Bitmaps printing with faded blue box around them


I installed X6 the other day and now and again I notice it prints a faded blue box around a bitmap. I have seen this happen in older versions of acrobat, but not sure why this would happen in X6. I went back to X4 and it prints just fine. Appreciated if anyone had any ideas?

I'm printing to a Xerox Docucolour 252.