never leave your precious coins on a machine that is connected to the internet.
use cold storage, move your coins offline, and only have online what you need to do daily payments.
malware, hackers, virus, etc, you are target, as your ip connects to the wallet, it get tracked and you will be attacked, sooner or later you will receive an email with a link, a download, an advertising, you will get infected and your coins transfer to another address.
electrum is not good, no wallet is good, only use them for small payments.