Your machine has no internet access. From Designer for Web when you edit/view a content wizard or a (q)form the editor first hangs on "Verifying Application requirements". After a long delay you receive a generic error. When you open the error log by clicking on "Open error log" you see the following error description in the "ERROR SUMMARY" section.
Below is a summary of the errors, details of these errors are listed later in the log. * An exception occurred while downloading the application. Following failure messages were detected: + The AssertApplicationRequirements method either did not get called or timed out. There is not trust decision before the commit.
The content wizard editor and form editor in Designer for Web are XBAP applications (a.k.a. XAML applications). XBAP applications are digitally signed. When an XBAP application is started, Internet Explorer will verify if the certificate is valid. Because the machine has no internet access, this operation times out and you receive the above error.
To prevent this issue you can disable certification revocation check in Internet Explorer. In Internet explorer go to:
1. Internet Options -> Advanced tab
2. Uncheck "Check for publisher's certification revocation"
3. Uncheck "Check for server certificate revocation"
4. Restart the computer.