Rendering and ReLinking

Hi there. I'm using the free version of Resolve. I'm on a PC with an I5, 16 gig ram, and a Geforce Nvidia 1070 graphics card. I know I need to upgrade to at least an i7 , but I'm managing ok. The problem I'm having is when I render this five minute piece I'm working on, it renders ok, but includes the odd frame of 'media offline' in the finished product.
The weird thing is, the media is definitely there, and playing whilst rendering, but yeah, the odd frame flashes up the 'media offline' message and thus gets rendered. What's more, if I try to relink the media and go to the precise folder I get the message 'No items match your search'. Even though, if I click on the 'open source folder' it takes me directly to the folder where said media is. Prior to all this, projects were failing to render until, following a youtuber's advice, I took off the default 'stop renders when a frame cannot be processed' in the 'preferences, which did solve the problem of failed renders.
So, yeah, now the project renders to 100%, but, like I say, renders frames of 'media offline' message. I would be most grateful to anyone who can help me resolve this (no pun intended). Thanks in advance.
The weird thing is, the media is definitely there, and playing whilst rendering, but yeah, the odd frame flashes up the 'media offline' message and thus gets rendered. What's more, if I try to relink the media and go to the precise folder I get the message 'No items match your search'. Even though, if I click on the 'open source folder' it takes me directly to the folder where said media is. Prior to all this, projects were failing to render until, following a youtuber's advice, I took off the default 'stop renders when a frame cannot be processed' in the 'preferences, which did solve the problem of failed renders.
So, yeah, now the project renders to 100%, but, like I say, renders frames of 'media offline' message. I would be most grateful to anyone who can help me resolve this (no pun intended). Thanks in advance.