I recently got infected with the Mirar toolbar, which is a browser hijacker. It's a bit like a trojan, I guess. I have two hard drives, each with 3 partitions and a copy of operating system/software on the boot partition. Drive 1 is used during normal operation with Drive 2 turned off (I spliced a DPST switch into the power wires to enable turning Drive 2 on or off). I can also set either drive as the master (I spliced a SPDT switch into the ribbon cable to do this). Both drives have the jumper set in the "cable select" position. I can set Drive 1 as master with Drive 2 also on, and I can set Drive 2 as master with both drives on. I can't turn Drive 1 off. The positions of these switches are changed only when the computer is off!
Whenever I get something bad on Drive 1 boot partition that I can't normally get rid of, I move all my documents etc. into the 2nd or 3rd partition, set Drive 2 as master, and "nuke" everything off the infected boot partition of Drive 1 (reformat). I then reinstall the operating system/software from a Norton Ghost image file, onto the boot partition I just nuked. Then I move my documents back onto the now-restored boot partition. I can also place backup copies of my Drive 1 documents onto Drive 2 when both drives are on. Both drives have the Ghost images needed to restore the boot partition on the other drive. Restoring a nuked boot partition from a Ghost image file is a lot easier than reinstalling the software one disk at a time! I have several Ghost image files, each of which were made at different stages of a fresh, uninfected operating system/software installation. The Ghost image files differ with regard to how much software was installed when each image file was made.
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A boy and his dog can go walking
A boy and his dog sometimes talk to each other
A boy and a dog can be happy sitting down in the woods on a log
But a dog knows his boy can go wrong