Virtual Box storage format error while installing Windows 10 tech. preview

Question

I'm trying to install the Windows 10 technical preview via Virtual Box on my Windows 8.1 32 bit laptop. After following the normal process of creating a new virtual machine by "New", when I go to "Settings" and attempt to load the Windows 10 technical preview iso which I downloaded from the Microsoft website, I get this error:

Failed to open the optical disk file C:\Users\Manish\Downloads\WindowsTechnicalPreview-x86-EN-US.iso.

Could not get the storage format of the medium 'C:\Users\Manish\Downloads\WindowsTechnicalPreview-x86-EN-US.iso' (VERR_NOT_SUPPORTED).

Result Code: VBOX_E_IPRT_ERROR (0x80BB0005)
Component: Medium
Interface: IMedium {05f2bbb6-a3a6-4fb9-9b49-6d0dda7142ac}
Callee: IVirtualBox {fafa4e17-1ee2-4905-a10e-fe7c18bf5554}
Callee RC: VBOX_E_OBJECT_NOT_FOUND (0x80BB0001)

I'm not sure how/why this happened. After reading up on this, one possible error (although not specific to this Windows 10 problem) seems to be that the downloaded ISO file may have been corrupt.

Just to make sure my downloaded iso wasn't corrupt, I went to this link and downloaded the MD5sums.exe file. According to the website description:

MD5sums calculates the MD5 message digest for one or more files (includes a percent done display for large files). By comparing the MD5 digest of a file to a value supplied by the original sender, you can make sure that files you download are free from damage and tampering. MD5 values are frequently supplied along with downloadable files. (Optimized implementation).

Either way, I used the downloaded iso file with this application, and got an MD5 sum, but when I headed to the Microsoft website from where I downloaded the iso, I see they have provided a SHA-1 Hash value instead:

73AC23AD89489855F33CA224F196327740057E2E

I'm not sure how to proceed further. Or if this is even a possible solution to the original problem, for that matter.

The configurations I entered in the new virtual machine in Virtual Box are:

System:
Base Memory: 1024 MB
Boot Order: Floppy, CD/DVD, Hard Disk
Acceleration: PAE/NX

Storage: 
Controller: IDE
IDE Secondary Master: [CD/DVD] Empty
Contoller: SATA
Sata Port 0: My Win10.vdi (Normal, 25.00GB)

I'm stumped now. Reading the error message, it looks like there is some version mis-match. However, I'm absolutely certain I downloaded the correct iso meant for Windows 32 bit machines.

Please help!

Solution

SHA-1 can also be used to determine the iso is an exact copy. Just download, and install a verification tool.

Ashs MD5-SHA1 Checker:

Try using Ashs MD5-SHA1 Checker, no installation needed just run it, and the browse for the file. It's free: http://sourceforge.net/projects/md5sha1checker/

If you find you are unable to browse for a file, try typing the location out by hand, or using control-c to paste it in (eg: "C:\Location\File.iso".)

Microsoft File Checksum Integrity Verifier:

If you'd prefer a command line tool try Microsoft File Checksum Integrity Verifier. It's free, but old, and unsupported; works fine on Windows 8 though. You can download it from http://www.microsoft.com/en-ca/download/details.aspx?id=11533 . Choose a folder to extract to then open your command prompt and use:

"C:\Location\fciv.exe" -v -both -add "C:\location2\file.iso"

Location being where you extracted the program too, and location2 being where the iso you want to check is located.

Comments

[magicandre1981]

use this shell extension for hash calculation and compare them: code.kliu.org/hashcheck

[Manish Giri]

I'm not sure how this works. First of all, I didn't see any way to just run it without installation. Second, when I downloaded and installed the application, nothing happened. Just like the first review given in the link you cite, when I attempt to open a file, the "Downloads" folder is opened by default, and there is nothing else.

[Robin Hood]

You should get an exe file, double click it to run the program, it should popup in the center of your screen, and in your system tray. sourceforge.net/projects/md5sha1checker/files/md5sha1checker‌​/… . Once you have it open, browse for the Windows ISO file.

[Manish Giri]

Like I said, when I downloaded & installed & opened the application & clicked on the icon "open a file for checksum calculation", the File Explorer just doesn't show anything. It's entirely blank. Can update my question with a screenshot, if you want.

[Robin Hood]

You can also type, or use control-c to paste in the location. Just click browse then paste (or type) in "C:\Location\File.iso", and click open.

[Manish Giri]

Well, somehow I managed to copy-paste the file name into the "File Name" box, and after that it just sits there. The progress bar is blank, very poor piece of software I must say. Can you update your answer with some screenshots of how to get this to work, after you have entered the filename of the desired file into the "File Name" checkbox?