I use PhotoMechanic for most of my browsing but I find ViewNX very helpful for no other reason than that it gives access to certain maker notes that other browsers can't deal with. I'm thinking about focus distance and the focus point. So I consider it "worth salvaging".
It's a good browser but I bought PM years ago when the old View was not such a good browser and got accustomed to living the high life on the browser front .
Let us know how it turns out. My suspicion is that if it won't run then it is most likely referencing one or more wrong DLLs.
If you play around with Process Explorer you will learn a lot about how Windows apps are "put together" in terms of their modular structure that is so reliant on all this DLL versioning. Plus many other interesting and entertaining things that Task Manager won't show you . I always thought Microsoft should have integrated that into Task Manager as some sort of "Advanced" display off of the Processes tab.
I'll close by suggesting that the internet is full of people complaining about how their registry cleaners hosed their OS build ups or certain apps. Most of what they remove is unintelligible hex keys so it's hard to look over their shoulders.
I think it's better to use tools like Process Explorer to find a problem like this and use reg cleaners only as a final "Hail Mary Pass" when all else fails. I've kept OS builds going for up to 5 years without ever using them. But I use tools to revert the OS partition back to some known working state when I have a problem (and problems do always happen from time to time). Something like Acronis but I use a somewhat higher end app called ShadowProtect.