However, you can look out for certain signs that your computer is infected. It's not always easy to determine whether your computer has become infected with a virus, worm, Trojan or spyware authors of malicious software do their best to disguise their work. Is your computer acting weird? Are boxes popping up on your screen, telling you your computer is infected? Are you hearing strange sounds? Your computer may have been infected with malware or a virus. This article is for small business owners who are concerned their systems may be infected and want to properly address the issue.