File>Properties

What is your project frame rate set there?

If it is 30p, probably that causes the issue (not exactly sure - just my quick thought)

Changed it to 60 fps, now it stops on preview as well.

That's weird. Any chance you could share a project? e.g. zip up the .veg file and media and share somewhere like Dropbox, Google Drive, mega.nz, wetransfer.com or mediafire.com. A stripped down project with just the snail media might be enough if that displays the issue and the other media is too large.

That's weird. Any chance you could share a project? e.g. zip up the .veg file and media and share somewhere like Dropbox, Google Drive, mega.nz, wetransfer.com or mediafire.com. A stripped down project with just the snail media might be enough if that displays the issue and the other media is too large.

that's the project (vegas 13) -

https://mega.nz/#!CF0WDACa!8V-rmSzgjCE6ks8qQdIEGh3SFyolvg7rSrkENQKGf0k

It includes the Red Giant Universe Swish Pan Premium OFX FX, so VP13 won't let me open it. But VP14 will let me open it, even though I don't have that FX installed.

I muted the upper track because the green was obscuring the snail. I played it and the snail kept moving to the end. I rendered it to Sony AVC/MVC Internet 1920x1080-59.94p and the snail kept moving to the end. I changed the project frame rate to 59.94 and the snail kept moving to the end.

Things to try:

• Set project properties field order to None (progressive scan). None of your source media here is interlaced, so you probably want that anyway.
• Set all the media to Disable resample. Help here.
• In Options > Preferences > Video set GPU acceleration of video processing to Off. Sounds like you've done that already, but I'm just making sure.

That still probably won't fix is though. It's a strange one. I suspect the 3rd party plugins might be the cause. You can submit a support request at https://support2.magix.com/customer/en/vegas/form

It includes the Red Giant Universe Swish Pan Premium OFX FX, so VP13 won't let me open it. But VP14 will let me open it, even though I don't have that FX installed.

I muted the upper track because the green was obscuring the snail. I played it and the snail kept moving to the end. I rendered it to Sony AVC/MVC Internet 1920x1080-59.94p and the snail kept moving to the end. I changed the project frame rate to 59.94 and the snail kept moving to the end.

Things to try:

• Set project properties field order to None (progressive scan). None of your source media here is interlaced, so you probably want that anyway.
• Set all the media to Disable resample. Help here.
• In Options > Preferences > Video set GPU acceleration of video processing to Off. Sounds like you've done that already, but I'm just making sure.

That still probably won't fix is though. It's a strange one. I suspect the 3rd party plugins might be the cause. You can submit a support request at https://support2.magix.com/customer/en/vegas/form

I already had field order set to None and disabled resample on all the media.

Disabling GPU helped now, but it's been the same with GPU disabled and even unattached physically, and it didn't work. (I tried different RAM options, multi-core rendering on and off, etc., but it didn't work as well). It's neither a GPU itself - as I said i tried to run PC without it. Can it be CPU or RAM, or even motherboard hardware issue? I recently reinstalled windows - and I had the same issue before reinstallation. I just don't now which part of hardware can cause such strange fps-render bug.

Disabling and enabling these effects (newblue chroma key, sapphire drop shadow) worked as well - but I'm still struggling - cause I want to get rid off this problem once and for all, I know it will appear again as it did millions of times before.

I very much doubt it's going to be hardware other than GPU. My money would be on the 3rd party FX. All you can really do is narrow it down by process of elimination. Try to establish exactly which FX, and whether it's only that FX with GPU on.

I've just had a thought that you might be suffering from this bug: https://www.vegascreativesoftware.info/us/forum/vp14-bug-still-image-animated-pan-crop-pre-pan-crop-fx--106639/

If you have a drop shadow FX on that snail, and it's before pan/crop, then you could see that bug. However my simple tests described in that thread showed that the bug didn't exist before VP14, so it's far from conclusive.

Previous advice to narrow down the cause of the problem still applies. Try to simplify the project as much as you can while still showing the bug. i.e. get rid of any unnecessary tracks and FX. Switch FX with native Vegas FX if possible and see if it still exists. The simple the project and step-by-step procedure that you can share to the forum and to Support, the better the chance of it getting it solved.

I very much doubt it's going to be hardware other than GPU. My money would be on the 3rd party FX. All you can really do is narrow it down by process of elimination. Try to establish exactly which FX, and whether it's only that FX with GPU on.

The thing is - I experienced the same with other versions of vegas and windows on my PC, and before i used newblue shadow FX instead of sapphire, but i had another problem with flickering and mixing layers (as this guy has, except mine was much worse - ) I don't think GPU is related to this problem as it was the same with unattached videocard (videos in my 1st post are rendered with no GPU installed).