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I am currently setting up my new Dell XPS 15 notebook and created a truecrypt volume (partition) on my harddisk, the OS is preinstalled Win 7 Home Premium. After reboot, Truecrypt wants to auto mount the partition, but the password is not accepted two times. On the third try, it shows that the volume header is damaged and that I should repair it by replacing it by the embedded backup header. After reparing, the problem seems fixed and I can mount/unmount multiple times without issues.

When I reboot the system, however, the volume header seems to be damaged again. Could this be some kind of recovery software that is preinstalled by DELL that changes partition headers?

EDIT: In the meantime, I found two things out:

  1. If I configure a drive letter for the unencrypted drive (which I don't want permanently), mounting the partition in Truecrypt works even after reboot
  2. If I don't assign drive letter and open the partiton in a HEX editor after reboot, I can see the word "RECOVERY" in clear text next to the beginning.

Please note, that there is a DELL recovery partition on my harddisk that is name Recovery, has no drive letter assigned and should not interfere with my encrypted partition at all.

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2 Answers

Check your BIOS settings for boot sector virus protection features, then shut those features off before you update your volume header.

These virus protection features included in the BIOS are a good idea, but can interfere with software that operates on boot sectors and partition tables (as some boot-based viruses from the DOS days did so) because the changes are prevented from actually being written to disk.

I suspect that you might have such a feature enabled in your BIOS, and that it's preventing your desired changes from taking effect.

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Ok, and why should unmounting/mounting then work as long as I don't reboot? (And I didn't find such an option) –  Tarnschaf Apr 18 '11 at 9:22
    
It could also from another software, putting their license activation data in otherwise unused bootsector, just like the Adobe licensing system, mentioned in Truecrypt manual –  Martheen Cahya Paulo Apr 19 '11 at 9:16
    
@Tarnschaf: Some BIOSes are programmed to simulate a successful write operation to keep the viruses at bay, but these changes are effectively wiped out at boot time. Martheen makes a very good point too. –  Randolf Richardson Apr 19 '11 at 19:19
    
@Martheen: This issue seems to apply only for very old versions of TrueCrypt and for system partition encryption. @Randolf: I would expect a BIOS acting like this to provide an option to deactive the feature but I didn't find anything.. –  Tarnschaf Apr 19 '11 at 20:16
    
@Tarnschaf: As I recall, the only ones I've seen that fake the writes all do have BIOS options to shut that off. I haven't seen it on any newer computers (only "boot sector protection" options that prevent writing and include a note that it needs to be disabled before installing an OS). –  Randolf Richardson Apr 19 '11 at 20:35
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Since I reinstalled Windows and the problems are gone now, I can only assume that a preinstalled application like "Dell DataSafe Local Backup" caused the problems.

The mentioned application is able to recover the system "without erasing personal files and data" an as such has to access the recovery partiton from time to time - maybe there is a bug that writes into the header of another partition as well.

Btw, the application crashed sometimes without being used by me at all - and the uninstaller failed as well. If anyone else experiences this problem I recommend to install a clean Windows and manually install the required drivers.

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