I did an extensive online search and reworded the query but only found solutions involving the split screen button. Stupidly, I didn't actually search this forum!
So I found the threads you posted in and followed Nick's thread and reset Vegas to the default settings.
I started Vegas as normal, imported a few of the PNGs and tried the effects. They worked as normal, so I thought it was fixed.
I then opened my project and the problem was back.
I closed it down and then opened 2 versions of Vegas, one with my project and a "clean" start.
I intended to somehow copy my edits across to the "clean" version, then realised I don't know how to do that!
It didn't matter though because the problem was gone again, though I have no clue why!

I say "was" gone because it is still behaving bizarrely.
I have a solid colour generated media which will go behind some text. I want to add the "Add Noise" effect to this. If I split the media and add the effect, the preview problem is back.
If I copy the media and edit the effect it works.
It ludicrous that one has to jump through hoops to use the program the way it was designed to be used.

I have had almost a week now of trying to solve problems instead of having fun being creative. Admittedly I have had a lot of great help and advice here, for which I am eternally grateful, but it really should not be necessary.
The program should just work, especially as I am doing nothing really intensive.

I am so disillusioned right now!

 

A couple thoughts:

1) Makes sure the preview playback quality is set to Good or Best (not auto or especially review). If the quality setting is preview (or gets adjusted to that automatically) I believe all effects are turned off to allow for smooth previewing.

2) Try setting dynamic RAM preview to 0. It doesn't sound like much but 400 is actually pretty high for Vegas. In past versions a common suggestion was to set it really low or to 0 when rendering.

Cornico, if you, please ;)

in case you needed to see the other info...

As always I want to thank you for your help.
I never want to take anything for granted.
I don't see anything I can change in regards to starting Vegas with another GPU.
I don't understand why I am un-checking the Nvidia card when surely, that is what it is there for? What does this actually do?
I also don't want to install older drivers, surely newer ones do the job better?
I am not arguing with you, it is obvious that you know far more than i, but I want a system which I can turn on and be creative with, not spend hours in forums, tweaking settings just to get average performance.

Are you saying that you had similar problems to me until you upgraded your GPU?
I would gladly buy it today if I could guarantee that it would solve the issues. My time is worth far more than the cost of the card (also, my wife and 1 year-old boy won't allow this for much longer!)

A Google search for "GTX 1050" came up with (what appears to be, I didn't check further) 5 different versions!

Are there any cards which Vegas is truly compatible with? Is it really as simple (however costly) as swapping out the GPU?
There are so many options for GPUs out there that choosing one is daunting in itself.
Do you see any other potential problems with my current set-up?

Thanks again for any feedback/help.
 

 

It is this option ,

if you don't have it, you cannot use option 1 and remain only option 2 and 3

I just found out that right-clicking the icon only works with the shortcut, so did as you suggested but didn't notice any improvement in performance. The integrated graphics card was set as default anyway and when I ran it with the Nvidia card, it still didn't show up in the "Preview Device" tab just Windows Graphics Card". Is this correct?
 

That card is than not accelerating the use of some parts of the program, f.i. the GPU accelerated FX's

It's up to you what to do, but if your CPU is fast enough it mostly is not a problem to deactivate that GPU in Options/Preferences/Video

I switched the GPU acceleration to "Off" but again, no noticeable difference in performance.
I'll try installing the older drivers now after understanding what you wrote about the newer ones.
I'm still confused though as I am to install older Nvidia drivers, but we are asking Vegas to run with the integrated graphics card anyway.
 

Are you saying that you had similar problems to me until you upgraded your GPU?
No, I did not upgrade my GPU, for what reason I should do that?
But now I have a new laptop with also another and newer NVidia GPU chip. The same happened on my desktop untill I totally upgraded that one with new motherboard, CPU, GPU and RAM Memory.

"This last option I used on my old laptap with the GTX 750M where, I had the same symtoms, now with the newer GTX 1050 the problems are gone and I can use wathever I want to use."
I now realise you meant you bought a new laptop.

It is up to you to decide what to do. Both remaining options will not change your possible workflow, but unchecking the NVidia can cause some more time for smooth previewing.

The option to roll-back driver is greyed out in Device Manager . How do I do this?

I'm downloading version 378.92 now (as you suggested pre 382), but still don't really understand how it could improve performance.
Let's see...

As far as I am aware, I have been logical throughout, have followed your advice and asked relevant questions so that I understand what I'm doing and can problem solve myself in the future. There seem to be so many variables that there is no "1 solution fits all" scenario.
I did read it back and I did ask about the video card in the same post, which may have been an error of judgement on my part, but this is the first time you have pointed it out.
Using any video editing program should not be so difficult providing one has the minimum requirements, which we have already established is true in my case.
I have no idea why you are now angry but I also appreciate that you are not here to provide me with one to one assistance.
I thank you for your help and advice and wish you well.

As one who asked Cornico to join in here, because his suggestion re drivers/FX window had worked (also), I'd just like to know if it worked for the OP.

I did an extensive online search and reworded the query but only found solutions involving the split screen button. Stupidly, I didn't actually search this forum!
So I found the threads you posted in and followed Nick's thread and reset Vegas to the default settings.
I started Vegas as normal, imported a few of the PNGs and tried the effects. They worked as normal, so I thought it was fixed.
I then opened my project and the problem was back.
I closed it down and then opened 2 versions of Vegas, one with my project and a "clean" start.
I intended to somehow copy my edits across to the "clean" version, then realised I don't know how to do that!
It didn't matter though because the problem was gone again, though I have no clue why!

I say "was" gone because it is still behaving bizarrely.
I have a solid colour generated media which will go behind some text. I want to add the "Add Noise" effect to this. If I split the media and add the effect, the preview problem is back.
If I copy the media and edit the effect it works.
It ludicrous that one has to jump through hoops to use the program the way it was designed to be used.

I have had almost a week now of trying to solve problems instead of having fun being creative. Admittedly I have had a lot of great help and advice here, for which I am eternally grateful, but it really should not be necessary.
The program should just work, especially as I am doing nothing really intensive.

I am so disillusioned right now!

 

I did so many things that I can't say for sure which step definitively solved the issue.
That said, the advice was solid and does seem to have cured the fx preview issue for now.
I am not confident however, that it won't simply come back.