How to keep tests from failing when running tests in parallel and switching iframes?

I'm currently mantaining a solution of tests using selenium and specflow, and I was running everything in parallel smoothly, sharing a sigle webdriver between browser(chrome) windows.

But now i had to add a couple of scenarios that involve switching between frames, and the tests started to break randomly when run in parallel due to elements or iframes not being found.

Anyone has had this problem and knows a good way to solve this?