It may be a faulty HDD or even a corrupt file in the OS, in that case, see if you can run "chkdsk /f", no quotes on the Start Run line.
chkdsk /f means Checkdisk, /f is an order to "fix". This action marks any bad sectors on the HDD for "do not use".
If you have to, you may need to re-install the OS, try to save any important files first to CD, and put 'em back later.
The following may not be your answer, but I hope that something here is beneficial.
No matter how fast or shiny computers might be when they are new, they all seem to get slower over time. That state-of-the-art PC you bought last year might not feel like such a screamer after you install a dozen programs, load it with antispyware and antivirus tools, and download untold amounts of junk from the Internet. The slowdown might happen so gradually you hardly notice it, until one day you’re trying to open a program or file and wonder, "What happened to my poor PC?"
Whatever the cause, there are a lot of ways to help speed up Windows and make your PC work better—even without upgrading your hardware. Here are some tips to help you optimize Windows Vista for faster performance.
Delete programs you never use
Many PC manufacturers pack their new computers with programs you didn’t order and might not want. These often include trial editions and limited edition versions of programs that software companies hope you will try, find useful, and then pay to upgrade to full versions or newer versions. If you decide you don’t want them, keeping the software on your computer might slow it down by using precious memory, disk space, and processing power.
It’s a good idea to uninstall all the programs you don’t plan to use. This should include both manufacturer-installed software and software you installed yourself but don’t want anymore—especially utility programs designed to help manage and tune your computer’s hardware and software. Utility programs such as virus scanners, disk cleaners, and backup tools often run automatically at startup, quietly chugging along in the background where you can’t see them. Many people have no idea they are even running.
Even if your PC is older, it might contain manufacturer-installed programs that you never noticed or have since forgotten about. It’s never too late to remove these and get rid of the clutter and wasted system resources. Maybe you thought you might use the software someday, but never did. Uninstall it and see if your PC runs faster.
Limit how many programs load at startup
Many programs are designed to load automatically when Windows starts. Software manufacturers often set their programs to open in the background, where you can’t see them running, so they’ll open right away when you click their icons. That's helpful for programs you use a lot, but for programs you rarely or never use, this wastes precious memory and slows down the time it takes Windows to finish loading.
Decide for yourself if you want a program to load at startup.
But how can you tell what programs load automatically at startup? Sometimes this is obvious, because the program will add an icon to the notification area on the taskbar, where you can see it running. Look there and see if there are any programs running that you don’t want to load automatically. Position your mouse over each icon to see the program name. Be sure to click the Show hidden icons button so you don’t miss any icons.
Even after you check the notification area, you might still have missed some programs that load automatically at startup. You can find and disable them using Windows Defender.
If you’re unsure about whether a program should open automatically at startup, you can try disabling it, restarting your computer, and then using the program. If that causes any problems with the program, you can go back and re-enable it to start automatically.
For instructions how to use Windows Defender to check for programs that open automatically, see Stop a program from running automatically when Windows starts.
NoteSome people prefer to manage which programs load at startup using the System Configuration tool. For more information, see Start System Configuration.
Defragment your hard drive
Fragmentation makes your hard disk do extra work that can slow down your computer. Disk Defragmenter rearranges fragmented data so your hard disk can work more efficiently. Disk Defragmenter runs on a schedule, but you can also defragment your hard disk manually.
For more information, see Improve performance by defragmenting your hard disk.
Clean up your hard disk
If you want to reduce the number of unnecessary files on your hard disk to free up disk space and help your computer run faster, use Disk Cleanup. It removes temporary files, empties the Recycle Bin, and removes a variety of system files and other items that you no longer need. For step-by-step instructions on how to do this, see Delete files using Disk Cleanup.
Run fewer programs at th