Why do I keep getting weird green bars and flashes after exporting videos???

Hey guys, I'm new to the forum, but looking for some help - when I export bigger projects I keep getting green bars and flashes (these do not appear on the timeline during the editing process, only after the export).

Any help or advice? I have noticed that this usually happens with bigger projects and especially when any photos are included in the project - but it happens with only video sometimes as well.

Attached is a screenshot of the flash

My computer specs are attached as well ... is my computer too old to process bigger projects?

No, this is going to be a codec and/or GPU issue, but you should be getting clean exports.
What third party plugins are you using in that Timeline?
What camera shot the footage your using?
Did you optimize or generate proxy media?
What drive is all your media and Libraries on?

Thanks for the reply:

I don't use any plugins with FCPX

Camera was a Canon 70D and also a GoPro Hero5\

I did not optimize anything, just imported straight from the camera card - this is what I've always done - is this not best practice?

Not sure how to generate proxy media either, or what that means.

The drive and media libraries are all on the computer hardrive - I back up the footage on an external after importing to FCPX, but everything is saved on the computer until exporting the project.

BenLandersMedia wrote: … just imported straight from the camera card ….

… using FCPX' Import routine (cmd-i), or by dragging .mts-files into it?

I used the "import" function via the FCPX menu.

Although I have done the drag and drop before in the past, will that cause problems?

With the photos - I found if I resized them to a smaller file (1080p) and then reimported them it solved the problem, could that be related to the problem I'm having with the video exporting as well?