That is what is called Ransomware. It's a scam but will disable your computer. Google Ransomware Removal. The most important thing is to protect your computer from getting it.
We have several tablets but I like Kindle Fire. DH loves his Komando tablet. Our old Ipad didn't last very long so we didn't buy another. I bought a cheap no name one at Walmart for the grands to use and it is still working great for their games and movies.