1. Install a registry cleaner software on your computer. Registry cleaners find infected registry entries, invalid DLL files and unused software entries. Scan your computer with a registry cleaner to have the program list the problems that need to be fixed. Repair and/or delete the registry entries that the cleaner tells you are safe to remove and clean.
2. Find computer malware problems by conducting a full-system scan with an anti-spyware and/or anti-virus program on your computer. Antivirus softwarescans computer systems and lists all virus, malware and Trojan infestations that it finds. Repair and/or remove those problems which the software finds.
3. Look at the list of computer programs and software you have installed. Open up the "Add/Remove Programs" part of your Control Panel if using a Microsoft Windows operating system. Delete and remove the computer programs that you don't recognize or no longer use. Some spyware and virus infestations hide in authentic-looking programs on your computer, but unknown programs on your computer should be removed.
4. Take note of any error messages popping up on your computer. Write these down or copy them to a separate location where you can refer back to them easily. Search for the error messages on the Microsoft "Fix It" website to diagnose problems at fixit.support.Microsoft.com if using a Microsoft Windows operating system. Download and install any automatic fixes which the Microsoft Fix-It website suggests.
5. Check physical connections between your computer power cord and the electrical outlet and all other computer peripherals. Printers, computer mice and audio speakers may not work properly or at all if they are not securely connected to the computer system.
6. Scan your computer with a system checker such as Crucial's System Scanner Tool at crucial.com if your computer is lagging or acting slower than normal. These types of scanners tell you how much random access memory (RAM) you have in your system and suggest compatible upgrades based on the results.