Unexpected slow performance
Frequent crashes or freezes
Pop-up ads appearing repeatedly
Programs opening or closing on their own
Browser homepage or search engine changed without permission
New toolbars, extensions, or apps you did not install
Unusual hard drive, CPU, or network activity
Security software disabled or unable to update
Files missing, corrupted, or renamed
Emails or messages sent from your account without your knowledge
Strange error messages or system behavior
Unknown processes running in Task Manager or Activity Monitor
Increased fan noise or overheating
Unauthorized changes to settings or passwords
Ransom messages or locked files
Antivirus scan detects malware
Boot time becomes unusually long
Internet usage spikes unexpectedly
Device redirects to unfamiliar websites
Accounts show suspicious login activity
System restore points or backups deleted