NetWorx installation doesn't proceed beyond "Welcome to the setup wizard"

When running the 5.5.5 setup I get to the "Welcome to the NetWorx setup wizard" screen, but after clicking Next nothing happens.
My OS is Windows 7 Professional 64 bit. Any ideas why it will not install?
I also tried running the standalone version, this seems to start OK, but I cannot change any of the settings or display any tabs other than the Main Settings Window.

It sounds like something is really wrong with your system or some antivirus software prevents the installer from working correctly.

Unfortunately there isn't much I can recommend other then restarting the computer, disabling your antivirus and trying again.

Also make sure the file you've downloaded is complete and not damaged. Our digital signatures on it should be valid - you can check in the installation package's properties:

The setup file has a different digital signature. Looks like a slightly older one. Has a Digest Algorithm of "sha1" and a date of 9th Oct
This was downloaded from the following site https://www.softperfect.com/products/networx/
I am using Avast free antivirus and Zonealarm firewall.

Older versions of Windows, including Win 7, only show sha1. To date, the latest published version of NetWorx was signed 9 October (23 October is from a screenshot of the latest build that hasn't been published yet). The main point is that the signature is there, is valid, and belongs to SoftPerfect.

In your case, the file seems to be complete and undamaged. Which means that the issue is most probably with your copy of Windows or the security products (Avast and/or Zonealarm). Security software blocking or interfering with installers and other programs are a very common cause of interrupted or unfinished installations or improperly functioning applications.

As advised above, try disabling them before attempting to install NetWorx. If that doesn't help, I'm afraid the isn't much else we can suggest.

Sorted. Apparently a previously installed version was causing the issue. Once I removed the old version, the new one installed OK. Thanks for your help.

It is strange that the old version was causing the problem. If the old version is properly exited as described in this article, it shouldn't interfere with the new installation.

Anyway, I'm glad to hear that the issue is now resolved.