Data Guard 365 has a post listing ten signs your computer has been infected by spyware and/or adware.
- Frequent, unauthorized changes in your browser home page.
- A flickering modem light when no one is online.
- While everyone gets junk emails (and one person's junk is another's must read) a sudden unexplained spike may indicate spyware or adware.
- A slowdown in launching applications or loading web pages.
- Unwanted redirects to websites.
- Intrusive banners that are hard to close.
- Unwanted pop-ups for possibly illegal offers. If personalized, an indication of spyware.
- 900 numbers - usually with a charge - may lead to identity theft.
- Foreign entries (unless you made contact first).
- Additional, unfamiliar browser toolbars.
Having a security system that will warn you of intruders is a good defense.