I think it is probably malware called "coupon companion". Random words on a page so up as a link. Usually anti virus will not catch this. To delete, go to your program folder find coupon companion and delete it. It's not a tough fix. Good luck.
A backup camera is always a good thing to have but a required replacement is years away. The D7K is said to get at least 150,000 shutter activations. So doing the math................ if you do 1K clicks per month, it should last 12 1/2 years. Happy shooting.
I purchased this lens (Sigma 18-250 OS HSM MACRO) about 2 weeks ago and am very satisfied. The OS or VR is very good and I have yet to use my tripod. The lock switch is very handy lso. Attached is a pic I took with it hand held at a friends place. I would highly recommend this lens.