Failed to Allocate Memory Buffer: Bug?

I’ve seen other people post about this. I just started coming across this error myself, and I’ve tried every solution I’ve found; nothing works.
I’m working with a somewhat lengthy clip (451 frames), and I’ve only kept one layer insert active out of the several I have, thinking that I could try multiple render passes. Every time I hit “Render” it goes right to the “failed to allocate memory buffer” message. My graphics card should be up to scratch.
Except just now, I changed the Output Layer Clip in the Insert Module, and it started trying to render. After twenty minutes, it never got past frame 1. So I tweaked one thing and now it doesn’t even give me the error message: it just sits there like a lemon. Checked my other layer inserts–nothing.