1. Visually Inspect Computer
Check computer case for damage 
and check all external cables connected to computer

2. Check Fans And Wiring
Check that all fans are working and that all internal cables plus wiring are connected
correctly then clean system as required

3. Check Input Output (Sound, Video etc.) Cards And RAM Memory Chips
Check that all cards and RAM memory chips are installed properly 

4. Check System For Disk Errors
Run diagnostic software to diagnose problems with hard disk drive and repair

5. Check System For Windows Operating System Errors
Run windows diagnostic software to check for windows errors and repair

6. Check System For Internet Spying Software
Check for programs that report back to Internet sites your personal information, 
e.g. The web sites you visit, your name, your e-mail address, personal information, 
where you are located etc. and remove them.

What is Adware/ Spyware ?

Adware / Spyware

and a solution

7. Check Anti-Virus Definitions And Security Software (Firewall)  
Check that your anti-virus definitions and security software (firewall) are up to date
These programs are what protect your computer from viruses and hackers by 
enabling your anti-virus program to recognize what virus is attacking your computer 
and to stop hackers from accessing your computer
 
8. Do Anti-Virus And Security Software (Firewall) Updates
If required update your anti-virus definitions and security program updates

9. Check System For Viruses
Run anti virus software to check system for viruses and remove any if found

10. Check For Windows Updates
Check windows update site to determine if you have the most up to date 
windows updates for your windows operating system

11. Do Windows Updates
If required do windows updates

12. Check For Program Updates
Check your other software programs to determine if you have the most up to date 
programs and if required do program updates

13. Run Disk Defragmenter
Defragment your hard disk drive to improve system performance

14. Recheck System For Disk Errors
Run diagnostic software to diagnose problems with hard disk drive and repair

15. Recheck System For Windows Operating System Errors
Run windows diagnostic software to check for windows errors and repair

16. Check Network Connections
If you have network card in your computer  
make sure that your computer is connected to the network 
and that the network connections works correctly

17. Check Printer(s)
Test printers to ensure for correct operation after performing service

18. Recommendations
Make recommendations to customer to improve their computing experience