I had the same problem recently. I had a client with a bad hard drive. When i tried to hook up the new hard drive as master and the old hard drive as slave to get some information off, NO BOOT. Remove the slave and it boot's up fine. What worked for me was putting the hard drive on the secondary IDE channel, if you have one.
If there is some useful information on the slave dive,
Get a copy of the diagnostic software from the drive manufacrturer. If its not really bad, it might eb able to repait the drive enough to get your data off. Otherwise, it may be covered under the warranty, some are up to 5 years (usually less) and they want you to run the diagnostics and report the results to them before they will send a replacement hard drive
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