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dd if=/dev/hda of=/home/richmondg/mbr_backup bs=512 count=1

Obviously, you will need to substitute the partition where your boot sector resides and also use your own username. Now let’s see just what we did there. dd just stands for disk dump, if means input file, of means output file, bs simply means bytes and count=1 tells the command to do this just once. It makes sense to save this out to some removable device, usually a USB stick, in which case amend the file path to suit so that /home/richmondg/mbr_backup reads, say, /dev/sda/mbr_backup or just copy the original backup to the external device.

Or, only copy the first 446 bytes. Why?

This could be a useful tip. If you change 512 to 446 in the above command you will only save the boot sector, but not the partition table. Why would you want to do that? The reason is that if you use 512 bytes and subsequently amend your partitons for any reason and then restore the MBR it will be out of sync. So, ensure that if you have made any partiton changes since your original MBR backup that you update that backup.

Restoring the MBR

Not surprisingly, in order to restore the MBR it is only necessary to reverse that original command which saved it. If you managed to hose the MBR you will not be able to boot up, so you can use a live CD to access your hard drive and read the backup off any removable media such as a USB stick. Here is the command:

dd if=/dev/sda/mbr_backup of=/dev/hda bs=512 count=1

Again, amend sda to read where you saved the MBR and run the command as root. If you wish to kill the MBR altogether, including the partition table, then you can overwrite it with a series of zeros:

dd if=/dev/zero of=/dev/hda bs=512 count=1

Researchers say that shortly after the Big Bang, the universe was loaded mostly with hydrogen and helium that was ionized -- too hot to remain in a stable state. For about 300,000 years, the universe expanded and cooled, and the gases began to recombine and stabilize to neutral states.

The universe then entered the dark ages, estimated to have lasted about half a billion years. All the while, clumps of matter developed. Then the first stars, galaxies and quasars formed. Quasars are incredibly bright objects thought to harbor black holes with masses billions of times that of our Sun.

Like morning sunlight burning through fog, the radiation from these new objects made the opaque gas of the universe become transparent by splitting atoms of hydrogen into free electrons and protons, say researchers, who call this period one of re-ionization

"The results are now telling us when this process was completed," said Sir Martin Rees, a cosmologist at Cambridge University who is familiar with the study. Rees told SPACE.com that the results are important for pinning down a time chart of the universe.

"It is as if the universe was filled by a dark, opaque fog up to that time," explains Sandra Castro, a postdoctoral student at Caltech and member of the team. "Then the fires -- the first galaxies -- lit up and burned through the fog. They made both the light and the clarity."

In the Keck observations, researchers found not only clear areas of sky but also large, leftover dark regions caused by the opaque gas from the dark ages. Scientists know that certain wavelengths of ultraviolet light are either absorbed or pass through hydrogen depending on its atomic state. In this case, the light emitted by the quasar was absorbed by intervening "neutral" hydrogen -- the non-ionized hydrogen that was the supposed fog of the dark ages. In other patches, some of the hydrogen had apparently been re-ionized, because the ultraviolet light passed through.

They say the conversion from an opaque to transparent universe was not instantaneous. It may have taken tens or even hundreds of millions of years for the earliest quasars and galaxies to burn through the cosmic fog.

Q. I have tried all the tools from your Patented Spyware Removal System and have managed to find and remove quite a lot of spyware. But I am still bedeviled by Internet demons that redirect my Google searches to various ad sites. Is there anything else I can try?

A. The fight against spyware is an ongoing struggle for all of us who use Windows based computers. Seems that the vermin who craft the malware are constantly looking for new ways to compromise our computers and are getting better and better at avoiding detection and removal.

Fortunately, there are still good software programmers who know our plight and are developing and updating tools needed to combat this digital scourge.

One of the more recent programs I have discovered is Combofix. In fact, I just used to to solve the very same issue you are describing and I have even updated my Web site to include a link to the program and a tutorial on how to use it.

It can look rather intimidating to the computer novice, but it's rather straightforward and seems to be very effective at removing spyware problems the other programs miss.

• Is there a safe-and-easy way to repair the boot sector without losing the information on it?"
  



Probably, yes. If it's an XP system, you can use the XP Recovery Console's fixMBR and fixBoot commands to rebuild the Master Boot Record (MBR) and repair the damaged Windows boot sector.



The information you'll need for XP is in Microsoft Knowledge Base article
314058,
"Description of the Windows XP Recovery Console for advanced users."



Vista's version of the Recovery Console is called the Windows Recovery Environment (RE) and operates quite differently. The Bootrec.exe tool in Windows RE serves a function similar to XP's fixMBR and fixBoot commands. Bootrec.exe lets you troubleshoot and repair various boot and startup issues. (BTW: Windows 7 uses the same Windows RE as Vista.)



For more information, see MS KB article
927392,
"How to use the Bootrec.exe tool in the Windows Recovery Environment to troubleshoot and repair startup issues in Windows Vista."