While it can be argued that in a corporate environment, where everything is ghosted and backed up, a reinstall is much quicker and more efficient than taking the time to troubleshoot problems, especially in the case of a nasty virus or things "just not working" right.
However, when your machine is acting up and you don't have backups of your photos and so forth, the thought of booting off of that XP CD and wiping partitions and starting over (then doing service packs, software, etc. etc.) is a daunting task at best.
Before you give up and start over, though, there are many many things that you can do to attempt to recover your windows XP install. Here are some of them.
1) Make sure it's really an XP problem. In other words, if you're getting lockups, that could be a heat issue instead of an XP issue. Make sure your heat sinks are clean; all the fans are turning, and that the system is relatively cool. This includes the fan on your video card, if you have one.
2) Have you added any hardware to the computer recently? Memory, for example, if it is the wrong speed will cause registry errors. I know; it's weird, but I've seen it more than once. If your problems started when you added or changed hardware, start there. Remove/uninstall the hardware and see if the problem goes away.
3) Have you added any new software? Search on the net for known issues with new software; do service packs or updates if they are available. Try uninstalling the software completely, and see if the problem goes away.
4) Is your anti-virus up to date? AVG from Grisoft is a great free anti-virus. ClamAV is also a decent one. If you can't get your anti-virus software to run, try going to housecall.trend.com and use their online virus scanner. You won't even need to install any software! Also, remember that just because ONE anti-virus (especially norton's) doesn't report a virus doesn't mean you don't have one. I have run a combination of AVG and Housecall on a virus-infected machine, and they BOTH found viruses the other didn't.
5) Have you checked your hard drive for errors? Running a complete scandisk, including looking for bad sectors, can head off hard drive problems before they become too serious. It never hurts to check.
6) Try a couple of these commands to REPAIR windows, before doing a REINSTALL. a) If your internet isn't working, go to a command prompt (Start --> Run --> CMD) and type: ipconfig /flushdns <Enter> netsh winsock reset <enter> .... then reboot. Also, clear your temporary internet files and cookies. b) If windows is having other problems, try this one: Start --> Run --> SFC /SCANNOW ... this will check all of the files that windows installed in your \windows\system and \windows\system32 to make sure they are up to date, present, and undamaged. After you run SFC, reboot and check for windows updates again.
7) Use a good cleaning tool. I like ccleaner (www.ccleaner.com). It will go through and remove all your downloaded service pack files (wasting space), empty your trash bin, temporary internet files, cookes, everything. It also does a complete registry scan and repair, and allows you to uninstall just about ANYTHING, including those programs that don't show up on your add/remove programs list.
8) Before doing a complete reinstall of Windows, try repairing it. To do this, boot from the CD. Do not take the first "R" choice, which is "Recovery Console". Continue along like normal, but Windows should find your windows installation on the hard drive, and ask you if you want to repair it (The second "R" in the process). Doing this will essentially wipe out the windows installation files, and reinstall windows WITHOUT removing all of your programs, files, and settings. You *WILL* need to check for updates again and install them after this process is complete.
** PROTECTING YOURSELF **
I can't stress the importance of a good anti-virus program; but a good spyware scanner is also important. SpyBot Search & Destroy is the one that I use most, but there are others out there.
Additionally, using Windows Defender will stop a lot of programs from automatically installing. Beware of toolbars, add-ons, and so forth. If Windows Defender asks you if you want to make a registry change or allow a program to run, and you're not dropping in a CD to INSTALL a program, tell it "NO".
*** CONCLUSION ***
Hopefully this FAQ will give you some alternatives to "Dump windows, reformat, and reinstall". Personally, I get frustrated when the response in a forum is "Reinstall windows". That's not an answer. That's a surrender. Learn how Windows works, what's going on behind the scenes, and you'll be better off in the long run.