Unexpected slow performance
Frequent crashes or freezes
Pop-up ads appearing outside your browser
Programs opening or closing by themselves
Unknown apps, files, or toolbars appearing
Browser homepage or search engine changing unexpectedly
High CPU, memory, or disk usage when idle
Antivirus or security software being disabled
Emails or messages sent from your account without your knowledge
Unusual network activity or internet usage
Files becoming corrupted, missing, or encrypted
Security warnings or blocked access to websites
Strange error messages
Computer overheating without heavy use
Passwords or account logins being changed unexpectedly