Which of the following is a sign that your computer may have been infected with malicious code

1. Frequent crashes or system errors

2. Unexpected slowdowns or performance issues
3. Unexplained changes to settings or files
4. Strange pop-up windows or advertisements
5. Unusual network activity or data usage
6. Missing or corrupted files
7. Unauthorized changes to software or applications
8. Antivirus or security software alerts of suspicious activity.