If you want to mount an ISO file in Windows 8 but you get the error Sorry there was a problem mounting the file try this
Updating Windows 8
1. Step Apparently, Microsoft patched this bug with the last update (November 2012)
2. StepOpen the Control Panel and go to System and Security
3. Step Next, if you see a red box saying You need to check for updates now, it’s possible you don’t have the latest Windows 8 updates yet
4. Step Click the button Check for Updates
5. Step Alright, now reboot your PC and you should be set
6. Step Try mounting an ISO file
7. Step Copy the ISO file to your local drive, do NOT mount from an external or network drive
8. Step If you still get the error “Sorry there was a problem mounting the file” make sure the ISO file is valid
9. Step Still problems? Download an alternative mounting tool like PowerISO or Daemon Tools
We explained how to mount ISO files in Windows 7 here that guide may be of help to you if you continue to have problems mounting ISO files in Windows 8
Solution, at least here. Use regedit to set defaults for *.iso to explorer.exe, for current user in software Microsoft windows currentversion explorer fileexts
In our case, use of various other iso editors apparently confused the system…context menu /right click solutions did not help, but regedit and reboot did.
In my case, the Mount worked fine, the iso’s showed as yet another (virtual) dvd drive, but the system through the error anyway, and the user had to know to ignore it and to look for that virtual drive. no longer, at least here.
sometimes its because that iso copy is set to “sparse”, that’s a whole different thing, a fresh copy (even of the sparse-set one as far as I can tell) resolves it…
Running win 8 with all updates through June 11, 2013. Still had the issue. The solution for me was to copy the ISO to a new location locally. I was then able to mount the copy fine. Apparently, copying removes a flag on the file.