Take care opening .Zip attachments in emails that look legit. There's a "ransomware" virus going around called Cryptolocker. It encrypts all your files, and they can only be retrieved if you pay $100-300 to the hijackers. Back up your files, every day.
I'm a professional software developer and just learned of this threat today, it is possibly the worst I've ever heard of. According to the experts opinions I've read, you *literally* cannot retrieve your files without paying those f*ckers.
The only way you can get the virus, though, is by deliberately opening the attachment. The email will be spoofed from your company's domain, and their grammar is actually good, so the email has fooled a lot of people.