1. CPU dose not power up. No lights or sounds on CPU.

• check power outlet and chords make sure that there is power and the chords are firmly in their sockets. Swap wires and eliminate the possibility of a loose connection
• If there's still no powering up, the fault may lie in the power supply. In this event its best you contact your nearest pc technician-because messing with that may be fatal if you are not careful.

2. CPU's processor light is on but no screen or sound of any kind

• Occasionally a voltage drop and motherboard problems can cause this kind of a symptom. Check the power.
• If that doesn't work try cleaning and dusting the inside of the PC
• If that also doesn't work the fault must be in the motherboard

• As you can see this problem is related  to the display section. the fault can be either with the VGA or monitor. First eliminate the possibility of a loose connection. secondly check whether there the VGA card is firmly in its slot. If it is an onboard VGA get another working VGA insert it into the AGP slot and see whether it works.
• Check and make sure the monitor is working properly.

5. Initial CPU boot is as usual but then an error message stating invalid system disk.

• This happens when the hard disk is damaged or there's a loose connection to the hard disk. Check whether the connectors are firmly connected remove and dust the connectors. If that doesn't work if you can, check your hard disk on another PC and see if it works.
• Some times the error message will say that windows cannot boot stating that a file is corrupt. This happens when one of the start up files have been deleted or are corrupt. You can fix this by starting your PC with the Windows Xp installation CD already in the CD drive. And boot your PC on the CD.
• NOTE:- Some times you might have to change the boot sequence in order to make the Pc to boot from the CD drive.
• Follow the on screen instructions and give repair Windows. Once it completes remove the CD and Boot your PC.

NOTE:- From this point onwards many software's also come into play. Viruses can cause a varying amount of different types of problems. However assuming that you have an up-to-date Antivirus program we'll look at problems other than viruses which can cause these problems.

6. An extremely slow startup

• Most often a slow start up is a result of many programs starting up at the same time your PC boots. so if you reduce the number of programs at start up, you can improve the boot speed. to do this you can either change the settings of that program, or you can use the system configuration utility.
• Some times one of the program that starts during start up maybe malfunctioning. To identify which program is giving trouble, go to task manager when the system boot is almost completed and identify the process that is taking the most of your CPUs power. Then locate to which program it belongs and then try to repair or reinstall that program.
• Registry errors can also contribute to a slow system startup. Since the registry is the place which has the configuration settings for your PC hardware and software, error there can seriously hamper the performance of the program and slow the PC during startup.

7. Even after startup Pc's Performance is extremely slow