U got a virus. Anything from a crypto miner to a password/credit card stealer.
Turn off the effected computer pull put the drive plug it into a separate computer as a secondary drive. Pull the data u need off the drive and make a backup. Then wipe the old system full reset(update BIOS if ur really paranoid). Then copy over ur backed up data. Do not copy any executable file from the infected drive.
Go change ALL ur passwords that u ever saved on that computer. And watch ur bank statements like a hawk.