I wonder whether doing the CC cleaner or reinstall parts would rectify anything as far as CC4 not loading on an ongoing basis, it may have been coincidentally that by taking these steps you wind up rebooting the PC, which itself may serve to restore Win 10 processes to a state whereby CC4 can load.
Hope everything functions normally, but if you run into this problem again, you could track whether rebooting your PC restores it to a working state.  Then after, if loading issues continued, review drivers to see if they are not older than the latest CC4 update.

Update: Resolved

Adjusting Windows Display Scale, Font and DPI is a compromise but will suffice. Now I can get back to work and hope that sometime in the future, Reallusion will add UI Scale Options in preferences.

BTW, I should point out to anyone who happens to stumble on this topic, there are additional settings in Windows Display > Advanced Scale Settings > 100 to 500 %, Windows says: not recommended! Why? if set too high, all the drop-down menus will not function properly, it's a complete mess lol. Not to worry it can be undone. Wow I'm done tweaking, I need to get back to work.

Thanks for the suggest regarding dpi, I forgot about that setting.
 
You guys are the best! This is a great community.

Greatly appreciate your help and this I'm sure will help others.

I forgot to mention that (it was late...:doze: ) but that is what I do, and as a result I have no trouble reading the UI text.

To change, right-click the desktop shortcut to iClone or CC, and select Properties and then proceed as shown below.

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On my display the maximum it can go is 225% and Font Size of 135% without cutting off some important areas of the UI. That said, what is sorely missing in CC4 is no option to adjust scale of widgets and fonts, fonts in the panels are so tiny I have great difficulties with that. I asked tech support about CC4 .ini file to see if tweaks can be done and if not? I will proceed with a refund. I did plan to also purchase iClone 8, but at this point in time, I hardly have words to express just how depressed I feel. I sincerely hope Reallusion can provide this ini tweak with plans for a future update that will include above mentioned solution.

About using a 4k monitor: I'm have a Dell 4k monitor (also 3840x2160) and it works without problems. I'm using a display scale factor of 125%. 

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Awesome! Thanks for chiming in, gives me hope -- I did a registry clean up and checked for updates (already updated) and of course I restarted to refresh the system. And guess what? CC4 Launched. I suppose the install did not go as smooth. Therefore, I highly recommend others who have launch issue to try the registry cleaner, I used CClean (not the best) but it got CC4 to launch.

Unfortunately there are other issues not related to my computer that are not yet resolved. Reallusion Tech Support is working on it, I hope will get resolved soon. I may have narrowed it down to lack of broader support for monitors. CC4 System Recommendation do not mention display/monitor. I did everything so far such as, checked for updates, tried the display scale settings, and of course I forwarded logs to Reallusion Tech Support. Wish me luck, hopefully I will get this mess sorted out soon so that I am able to access all important settings in CC4. I am using a Sony XBR 43 inch TV 3840x2160 native resolution (yes I know, it's not true 4K), it appears (literally) that only Reallusion is the issue because all other software such as Blender, Unity and Unreal Engine work fine.

My Suggestion to the Devs:
Make the panels in CC4 smaller, correct the scale issue to be compatible with all display/monitors. And all panels such as the Export to FBX dockable -- then have an option for one-click hide all panels -- rather than using the shortcut ctrl+6 because it removes the toolbar. That's fine for preview (ctrl+6) but not so fine for other workflow reasons.

Thanks to everyone for chiming in -- I sincerely appreciate it.

Hi,

You mentioned you were a experience computer user; If the program is not launching, check your event viewer to see if the program is throwing
a error...may give you a place on where to start looking for the error or something to get to support. Here an issue I was having with Reallusion Hub.

@3CPU
Does this resemble what is occurring in your case 
iC8 and CC4 Won't Load - Stuck on "Please Wait...."

And do indeed check what GPU driver you have, as Peter stated.  If outdated, it could be an issue, even though it worked days before without having changed anything. 
Also what might happen is over time Win10 shuts down or activates certain processes that may affect other processes from running, in my case rebooting is a workaround allowed me to access CC4 again.