TiVo HDMI connected to PC monitor flashes on/off

I just got a new Roamio Plus box (my fifth TiVo!) and I moved my old Series3 (w/ WD ext disk) next to my computer so I could leave it hooked up to my network to transfer what I can to the new TiVo. After doing that I figured I could watch the non-transferable stuff on my computer monitor. My PC monitor has VGA and DVI-D inputs and I use the DVI-D with an HDMI to DVI-D cable for my PC.



But when I plug the HDMI end into my Series3 I do get a picture, but it flashes back & forth between the TiVo screen and white noise every second or so. Even so, I am able to control the Series3 so I tried every Video Output Setting, from Native to 1080i, resetting the monitor (power on/off) each time, but the picture keeps flashing. Every couple minutes it will stabilize for a few seconds but then go back to flashing (to be clear, this is just the Series3 and my PC monitor, my computer is not involved).



Anyway, being that it's a Series3 it has both RCA & RGB output jacks, so would the easiest thing be to get an RGB to DVI-D cable (do audio separate) so I can watch the non-transferred stuff at my computer? Being that it's flashing like that I assume it isn't an HDCP issue, and just an adapter cable will work? Anyone have a link to the right cable I should buy?



Thanks.



P.S.

This is my first post in quite a while, what can I say, a TiVo normally just works!! :D