Shootie,
Am just making educated guesses in the dark; not knowing your system or its age. But when you take out a battery to replace it the CMOS often loses its settings. Generally, nowadays, on computers that are fairly new, this does not matter since the computer can recognize all the installed equipment. However, on older computers having new technology released after they were built, they may need some some "help" to use this new technology. Often, this involves drivers that install into the OS, modified boot routines on the drive, or changing a default CMOS setting.
The CMOS is where your computer stores information that varies according to hardware/user requirements and that must be in place prior to when it starts reading information on the boot drive and OS. That's why you have a battery in the first place; to store this information and, of course, to keep the correct time. One of these parameters is the hard drive configuration. Tracks, sectors, heads.
If these were not set to the computer defaults for reasons I mentioned in my previous post; then the computer loses access to parts of the disk. For instance if the drive had 210 areas (called sectors) to store information, a combination of sector, track, and head tells the computer where to go. In this example, the computer might have one of the following configurations (or others not shown below):
1. -> 1 Hd, 21 tracks, 10 sectors
2. -> 1 Hd, 42 tracks, 5 sectors
3. -> 2 Hd, 21 tracks, 5 sectors
The thing is, the computer doesn't care which you tell it because the drive's real configuration will almost never be one of the choices, it just needs to know a preferred addressing method (because of hardware, OS, or other limitations). For instance, maybe when your computer was built no hard drive had more than 21 tracks so the BIOS (which boots your computer, among other things) only has coding for recognizing up to 21 tracks. But now there's a new drive with 42 tracks. So in the CMOS you have to say the hard drive is 1 or 3 above. It doesn't matter which, but
if you tell it #1 and the computer defaults to #3, then when it boots up, it will possibly access the sectors in a different sequence, so that even though all your data is there, it appears corrupted. (This is probably not your problem since it probably would not even boot.) However, lets say that you get a new drive with 420 sectors. The CMOS does not have an option for 420 sectors to be defined, so a software program might be installed on a modified boot sector to boot to facilate the boot so that the OS could make use of the other half of the disk. In some cases, it might even change the CMOS parameters to facilitate it's efficiency. For instance, it might pick an option 4 that says it has 1 head, 7 tracks, and 30 sectors. In this case, if the computer defaults to option 1, 2, or 3; it won't find any sectors numbered beyond 5 or 10.
None of this is a big problem until the computer tries to fix itself and starts moving sectors around and can't find some or puts them in the wrong order, etc. Each time it does this, one file is corrupted that is being worked on and another is possibly corrupted that has it's space overwritten. (Never mind the FAT and root directory since I think you get the idea). Once these things happen, they are not recoverable (by financially feasible methods), although if it is caught in time and the CMOS set to it's old values, remaining files can be copied off the drive if it is mounted as a secondary drive.
If it is a hardware problem, these are frequently intermittent, at first, and turning the computer off and letting it rest overnight often resolves the problem, TEMPORARILY. However, if scandisk is allowed to run, it will try and fix problems by moving data from bad to good parts of the disk, even if it cannot read everything. Each file that it moves that it read imperfectly or incompletely becomes corrupted.
The bottom line is that you might want to have a professional look at it if there are important things because once corruption starts, often each new attempt to fix the problem (if not the exact fix required) causes more corruption.
Good luck,
Steve |
