Ok, finally downloaded the link.
Had no problem installing playing, nor getting back to the flash version.
Had it installed in less then 4-5 minutes.
My computer is emachines(older)dual core AMD Athlon II 235e 6G's of DDR2, it does have a GTX570 GPU installed.(actually, after the install, I didn't notice that much difference on WGT, but wasn't gonna pull it back out and have it sitting on a shelf) Win7(sp1 but missing a number of updates)
Downloaded the link Champ supplied on the first page, it downloaded to my normal spot on the hard drive. I went to that spot and sent it to the desktop as a icon. I installed from that icon. It does not ask there for administrator, I just used the install at the top of the list. The game did hesitate slightly at times(think it was doing things in the background), but installed fine. It did update right after the install, I think I saw that it did 59/59 updates. It gave me the opportunity to sign in, which I did(I was not signed out of the flash version) It loaded, took me a bit to figure out where I wanted to go to play a single player stroke play, but found it actually with no problem. Changed some of the options before going into a game, had no problem. Got into a game, played 2 holes, then finally discovered how to quit the game which I did. Once game closed and back to desktop went to my game client browser(slimjet) it opened just fine and I was still signed in and played a couple of flash holes(no problem in doing so)
I too run the free version of Avast, never did I disable it or close it down, neither during game play or during the download/install.
I do have window firewall turned off, but I am online behind a Arris modem and linksys router.
I can if need be try this also on a custom windows 10 machine I just built(but I don't really desire to, I think enough of you have already done this with win10.
This is not a real powerful computer, don't even know if it would actually meet the minimum requirements.(it doesn't now)(most games if I go to can I run it, will not meet minimum. I can run some steam games now, that I have the 570 gpu(it had onboard)(nope didn't buy for this, that was in my other gaming rig before I updated it to a 1060 gpu)
Some of what I have read in here, doesn't make sense with the install problems.
Oh yeah, almost forgot, the game appears to be running version 1.52.0.1877572_D.
After it was all said and done, I ended up with 2 icons on my desktop....WGT Launcher setup and WGT Launcher.
So some of the things I have seen asked for within this thread have already been changed/added.
Maybe try doing this. Completely uninstall and get rid of everything concerning this download, including the original link you use for download(I use Revo, for most files/directories/ and registry entries) Re-download the link and start all afresh.
PS...just checked concerning the avast firewall, unsure, didn't actually find anything concerning to tell me if it is on/off. What is new is Avast Omni. Didn't turn it on or activate. May look further into this later(think it happened the last time Avast Updated), I do use its browser in bank mode with other things.
PSS...checked this morning, windows firewall IS TURNED ON, have not changed any of the inbound or outbound rules(chitpot full of them) Uninstalled with no problem, checked on both Revo and CC, it appears that there was only 1 registry entry that was put there. The WGT uninstall cleaned pretty good.