1. Electrum
2. Windows
3.A normal laptop x64
As said, your computer is probably infected.
For the future: cleanup, or, better, reinstall (make sure though you have at hand your windows key).
In the next transactions always check/compare the copy/paste addresses (and much more than just the few first characters in the addresses).
A separate partition with a Linux (maybe Mint is easy enough) only for Electrum/transactions could be an idea to think about. Or even a hardware wallet. (this because if you got today a clipboard malware, "tomorrow" you may catch something much uglier)