There are many warning signs or symptoms which show that a computer is infected with a virus, some of which are as follows:
- Slow computer performance: The machine may work slowly, e.g., it will take more time to open or shut down the computer or while opening a file, document, computer application, etc. The operating system and internet speed may get slow.
- Frequent pop-ups: A virus may cause unusual frequent pop-ups on your window.
- Hard Drive issue: The hard drive may exhibit unusual high activity even when it is not in use. It may cause unwanted changes to your hard drive and may freeze or crash this device.
- Frequent crashes: One may experience frequent sudden system crashes while playing games, watching videos, or doing some other work using the infected system. A blue screen appears when it crashes.
- Unknown programs: Unwanted programs may open or start automatically when you start your computer. You can see these programs in your computer’s list of active applications. Sometimes, the window shuts down unexpectedly without any reason.
- Unusual activities: Your machine may perform differently, such as you may not be able to log into your accounts, to delete the corrupt files, and Blue Screen of Death (BSOD) may appear frequently, and more. Furthermore, the hardware, software, or OS may start malfunctioning leading to crashing the system abruptly.
- Impaired security solutions: Sometimes, security measures taken by you, such as antivirus may not work smoothly due to virus attack on your computer.
- Network issue: Sometimes, you experience high network activity even if you are not connected to the internet and vice versa.
- Unnecessary advertisement: We often see advertisements while browsing, but if you see them even when you are not browsing, it may indicate a virus on your computer.
- Display problems: You may experience different colors in your display if your computer is affected by a virus.
- Affected Applications: Some viruses are developed to affect specific applications. Consequently, some applications may not work on your computer if it is infected.
- Blocked by Antivirus Sites: An antivirus site may deny access to a computer that is infected by a virus.
- Dialog Boxes: Many dialog boxes keep appearing suddenly on your screen.
- Printer Issues: A printer attached to an infected computer may print documents without getting any command or in an inappropriate manner.
- Changed Homepage: Your home page may get changed without any effort from your side. For example, you may see a new toolbar on your screen, and you may be redirected to a different web address instead of the page visited by you initially.
- Strange messages: One may see strange messages on a computer screen such as error messages, e.g., “cannot rename “folder” as a folder already exists with this name”