There is bast history of wallets being infected with malware. The altcoin section is a dangerous place to be when it comes to downloading clients. There is a ton of evidence of people trying to pass wallets as legit when they were infected with viruses, RATs, malwares, keyloggers.. you name it. There's also this trick of infecting the computer to paste addresses that belong to the hacker. So when you think you copied your address and paste it, you are pasting his address so you send him BTC.

In general, always be wary when you download anything that isn't signed by reputable people.