Well this is wrong really startup isnt simple. It meas that your operating system has to load all of your drivers and everything that you set up in a certain order. If its not in this order or something happens incorrectly like a malfunctioning driver or a program not installed propery then you will have either a slow start up or no start up...simple as
Blue screen of Death!!
This in PC terms is hell on earth. Everyone fears the blue screen of death
This above is a typical blue screen of death. Its gives you lots of information but to the untrained eye its means somethings buggered up but i dont know what?
Heres how to fix some issues:
1. How To Fix Your Computer?
The reason why your computer is showing the blue screen is because of errors in the registry. To clean this area of the computer, you will need to download a cleaner software. It is not encouraged that you attempt to fix your registry yourself because it can be very dangerous.
2. Why Does The Blue Screen Of Death Occur?
When you install software and new programs in your computer, new entries and other changes will be made on your registry. As more and more entries pile up, some of them may become infected with spyware, or go missing because the system does not always restore them. As a result, when the programs that use the entries need to run, your computer may suddenly process very slowly, or worse, the blue screen of death happens. All these problems can be cured with a registry cleaner.
The amount of changes to your registry is dependent on the user's amount of usage of the computer. A newly purchased computer will usually run very quickly, but after a few months, users find that their computer's processing speed may start to slow down. This is the effect of a poorly maintained registry.
3. So what registry cleaner?
I use the in built registry cleaner in CCleaner. Its free and really really easy to use. It will clean almost every registry issue. I have already written instructions on how to use this program so take a look here: CCleaner
Slow startup:
A slow startup doesnt necesarly mean a virus but then sometimes it can. Unnecesary programs loading etc can all be reason for a slow startup so heres how to help it:
If you no longer use any application, you can uninstall it. To do this click on the "Start" icon at the bottom left of the computer screen and then click on the "Control Panel". Double click on the icon "Add/Remove Programs" and you will see a list of all the currently installed programs. Select the program you want to uninstall, and click the "Remove" button. Some files are shared across several programs so if you get a message that asks you if you want to remove them, click the "No" button to be on the safe side.
The Windows® XP operating system comes with a system tool called a "Disk Defragmenter". It is used to rearrange files stored on your computer hard disk into one continuous sequence instead of being arranged and stored in different places on the hard disk. Your computer hard disk will be optimised to function at its best if all the information is stored in an ordered way. Unfortunately, programs do not always place items in the optimal places on your hard drive, and when you create, update, or delete files or programs, your hard drive gets fragmented. To get all the information ordered again, you can defragment your hard disk by running the Disk Defragmenter system tool. To do this click on the "Start" icon at the bottom left of the computer screen and then click on "All Programs", "Accessories", "System Tools", and select "Disk Defragmenter".
Disk Cleanup is a Windows® XP operating system tool that lets you clean out and purge those useless hard disk files that accumulate over time. The most common areas purged by the Disk Cleanup tool include: temporary operating system files, temporary Internet files, temporary program files, downloaded program files, Recycle Bin files, and Setup log files. To run Disk Cleanup click on the "Start" icon at the bottom left of the computer screen and then click on "All Programs", "Accessories", "System Tools", and select "Disk Cleanup"
The last few instructions are also applicable to Windows Vista users
CCleaner again!
I know i go on about it but its great again for these problmes see my other page for more info
Go to start, run and then type in msconfg exactly as show there.
Vista users may need to enable the run box:
1. Right-click on the taskbar
2. Select Properties
3. Click on the Start Menu tab
4. Click on the Customize button
5. Scroll down and check Run
Now click on the startup tab at the top of the box. You will been greated with a screen like the one above. It will show you all the programs that are loaded and ones that wont load when you are starting you PC. If you see above that all the programs from mobsync to Arco tray will load on startup and anything under there will not. This is because the ones at the top have the tick box at the side clicked. This will allow the program to load while the ones nearer the bottom do not have this box clicked so the program will not load. If it does you are infected and you should see my other page on removal.
In Windows XP, all of Windows' essential programs are loaded through something called "Windows Services." This means that most of the startup items you see in XP can be turned off. However, a good rule is to disable only those programs that you recognize and don't need to have running all the time. When in doubt, leave it . Or,search for it in this list at http://www.sysinfo.org/startuplist.php. This will show you which items are needed and what arent and then it will allow you to disable or enable accordingly
Vista.
.There are some additional security features you may see when running this program

If this box appears then simply click continue and this will allow the program to run. 
Then on both XP and Vista you will then be met with this screen. You may either select restart or exit without retart. Either way it doesnt matter what you click. Restart will restart you pc there ant then and apply changes when it start up. Exit without retart will allow you to continue to use your PC and will make the msconfig changes when you turn on your PC next time