Hi Howard....Had a similar problem last week...I had run defraggler around the same time but dont think it would of been the cause as I booted up a couple of times after running the programme and have run it since..
I have Windows XP..
Another stab in the dark is your Hard Drive could be getting old and you are due for a replacement.
They are pretty cheap and it is a easy job to transfer your complete system to the new drive.
(I am getting a computer mate to do it with one of his programmes shortly as My drive is quite old and have to boot up at least 3/4 times each time I turn on my computer before it loads up - anyway that is another story but worth mentioning)
A lot of people leave it until it is to late and as stated it doesnt cost much for a drive these days.
I recommend a Western Digitial drive as Seagate can have problems occassionally.
Now back to your problem (I hope)...
I solved my problem by inserting my XP PRO installation disc and doing a recovery. Fixed it promptly. Again I didnt do it my Computer geek mate did it but pretty simple..
Once the disc is in just goto "learn more about the setup processes" and that should explain how to do a recovery.
It does go on a lot about Safe mode so if you can get into that give it a go first..
Here is a cut and paste from my XP Pro setup process..
Hope it helps because I know how you feel.....
Quote
Troubleshooting problems with multiboot systems
These additional troubleshooting ideas might help you resolve your issue without having to call technical support:
Errors with Internet Explorer:
When you start Microsoft Internet Explorer, the browser might quit and you might receive an error message that is similar to the following:
iexplore caused an Invalid Page Fault in module kernel32.dll
This error might occur if you install multiple operating systems on a single volume. To resolve this issue, install each operating system on a separate volume.
You cannot configure your computer to start both Windows 95 and Windows 98 (or Windows Millennium Edition)
You cannot configure a computer to multiboot Windows 95 and Windows 98 (or Windows Millennium Edition) because those platforms use the same boot file. Therefore, multibooting Windows 95, Windows 98 and Windows Millennium Edition at the same time is not supported.
The boot menu does not appear upon startup
When you start your computer, the boot menu does not appear and you are unable to start Windows XP. This problem might occur if you install Windows 95, Windows 98 or Windows Millennium Edition after you install Windows XP. To resolve this issue, repair or reinstall Windows XP.
For more information about multibooting with Windows 2000 and Windows XP, see Multibooting with Windows 2000 and Windows XP (http://www.microsoft.com/windows2000/techinfo/administration/management/mltiboot.asp).
Also, see Microsoft Knowledge Base article 205287.
Repair or recover a system
You can repair or recover your system in several different ways. Instructions for each method are below. Try the methods in this order:
Revert to the "Last Known Good" configuration.
Start the computer in Safe Mode and try to fix the problem.
Use the Windows XP Recovery Console.
Use System Restore.
Use Automated System Recovery (works for Windows XP Professional only, not Windows XP Home Edition).
To use the Last Known Good configuration:
If Windows XP will not start, you can restore your system to the Last Known Good configuration ? in other words, your most recent settings that worked. Here's how:
Start the computer and then press the F8 key when Windows begins to start. The Windows Advanced Options menu appears.
Use the arrow keys to select Last Known Good Configuration (your most recent settings that worked), and then press ENTER.
If a boot menu appears, use the arrow keys to select Microsoft Windows XP, and then press ENTER. Windows XP restores the computer to the most recent restore point.
To use the Windows XP Recovery Console:
The Windows XP Recovery Console allows you to:
Use, copy, rename, or replace operating system files and folders.
Enable or disable service or device startup when you next start your computer.
Repair the file system boot sector or the Master Boot Record (MBR).
Create and format partitions on drives.
Here's how to use the Recovery Console:
Insert the Windows XP CD into your CD-ROM drive, and then restart your computer.
On the menu that appears, click Install Windows XP.
Press R to repair the selected Windows installation.
When you use the Recovery Console, you will be prompted to enter the Administrator account password. If you enter an incorrect password three times, the Recovery Console will close. If the database that contains user account information for your computer is missing or damaged, you will not be able to use the Recovery Console.
After you enter your password and the Recovery Console starts, type exit to restart the computer. The Recovery Console has some other limitations. For details, see Microsoft Knowledge Base article 314058: Description of the Windows XP Recovery Console.
Best of luck mate