How exactly should you go about deciding what to do to your computer in order to fix it?
The answer depends on exactly what your computer is doing. This page will help you decide what to do.
I have this information elsewhere on this site, but I will repeat it here:
Generally speaking, only 2 things that can be wrong with your computer:
1. There is a hardware problem.
In this case, the failing piece of hardware will have to be replaced.
2. Windows is infected and unstable.
Spy-ware and viruses can often damage Windows so badly that your computer will run very poorly and you may not even be able to get on the Internet. In this case Windows or the damaged software will have to be repaired or reloaded.
Hardware problem: If you have a hardware problem on your computer, no amount of repairing or reloading Windows will fix the problem. Take a look at Event Viewer and make sure you do not see anything awry there. How to use event viewer
The Safe Mode Test:
Generally, if your computer is slow when you try to use it normally, reboot it into safe mode. If your computer still runs badly, your issue may be hardware. If it runs like it is supposed to while you are in safe mode, and slower when in normal mode, your problem is probably virus and spy-ware related. It could be a driver issue, but unless you just recently added a piece of hardware, it is more likely that your issue is Malware.
Windows is damaged: Over time, Windows becomes unstable. Over time Windows will become infected with spy ware that will cause damage to Windows. Software will be installed or uninstalled and leave small damage behind. Incorrectly shutting down your computer will damage Windows. All of this leads to the same place: Do you clean, repair, or wipe and reload Windows?
You should take into consideration the following information:
If your computer jacks up immediately after installing software or hardware, remove whatever you just installed.
If your computer jacks up immediately after plugging in a USB device, remove that device, and try another USB port.
If you are getting .dll errors, wipe and reload.
If you have a rootkit, wipe and reload.
If you are in a hurry, have saved everything you need to, and you have all your drivers and software on a flash drive or disc, wipe and reload gives the best results and will take MUCH less time. Be sure to do a full format.
If your computer is running a little slow, and you just want to tune it up before it gets worse, a cleanup is in order. You can use the cleanup procedure on this website if you wish to.
If you did the "Safe Mode" test mentioned above and your computer runs better in safe mode than in normal mode, you can probably clean your system. If you did not do it yet, do it now.
If your computer is running poorly and having trouble getting Windows to even load fully, you may need to repair your system. BUT you cannot repair an infected computer. So you have to clean it out first, then attempt the repair.
It is entirely possible that you will spend a couple of days trying to clean and repair Windows and then still have to wipe and reload. I have done this many times.
If you cannot save your data, and get copies of your drivers and software, you should not wipe and reload your system, Do a malware clean out first and then a repair installation if necessary.