@zalex108 : with iboit uninstaller or ccleaner, same problem
@leocg : same problem with the portable version

I can use only the Beta Version of Opera... I will stay like that.

I try to install the Beta Version & it works...

Version : 46.0.2597.6 (PGO)
Flux de mise à jour : beta
Système : Windows 7 64-bit

After a reboot, same problem. When I try to open Opera : nothing happens.

I downloaded the FTP version "Opera_45.0.2552.881_Setup_x64.exe"
-> http://ftp.opera.com/ftp/pub/opera/desktop/45.0.2552.881/win

The installation went well to the end. But when I try to open it, nothing happens. I will try to restart my computer.

Exactly the same problem with the offline installer.

I can install any programs I want without problems.
package downloaded from the official website : http://www.opera.com/fr

I tried to install as an admin (with my windows session & I'm admin of the domain), after on the domain admin session, with the local admin, with a basic user, with a user with credentials, and with a user with full credentials. Everytime I have the error message.

I try to install on an other computer of my society & I have the same problem...
Really I don't understand why!

I take the last package installation.

This is the first time I have installed Opera

No one has had this problem?

I can't install Opera, I have an error message when I open the installation package.

"Windows is unable to access the specified device, path, or file.
You may not have the appropriate permissions to access the item."

I tried to download the package on my desktop, in the download folder, and in any folder on my computer.
Always the same error message.
I'm connected to an enterprise domain and am administrator (from my computer, domain and company). Whether I try to install it on the "local" or "domain" administrator session, with a basic user or administrator, I still have this message.

I use a Windows 7 Pro 64bits SP1 with all the latest updates.

If someone has already had this problem and solved it, I'm taker of his solution.

Thanks you!