system
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OK - just to add to my last post and revise my statement that the USB tool works … It 95% works because is does not seem to write a valid Master Boot Record to the USB drive!
The following was done using ‘removable’ flash drives.
I used a 2GB USB flash drive which I had previously used for HitmanPro. When I booted from it after running the Avast USB installer tool - it still booted to HitmanPro. The drive itself contained the correct Avast files and folders. To prove it, I installed a standard MBR using RMPrepUSB and it then booted to Avast Rescue just fine.
In a 2nd experiment, I wiped the bytes in the MBR but left the partition table intact on the working Verbatim drive I used earlier. I then reinstalled Avast on it and the MBR was NOT changed and of course it did not boot.
If I wipe a USB flash drive using RMPrepUSB - Clean, then the drive is not listed by the Avast USB tool. So it needs a partitioned/formatted USB drive but it assumes that it contains boot code in the MBR of the flash drive.
I suggest that people therefore format their flash drives using RMPrepUSB (as FAT32+HDD) or a similar tool to ensure that it contains valid boot code in the MBR (first sector).
If you format using Windows 7, it may format the drive as a floppy disk with no MBR and therefore it will not boot to Avast WinPE. You can check that it has a valid MBR and partition table using a suitable utility (e.g. RMPrepUSB - Drive Info - 0).
As many store-bought flash drives come ready-formatted and don’t contain MBR boot code, this may explain why it doesn’t work on some flash drives…?