Not come across a screen flashing response myself but how USB memory sticks or similar devices behave when they don't work, or work unreliably, in my experience, is random. It may depend on the version Xbox being used, I've not had the inclination to test that out though. I suppose there might even be a specific BIOS feature that causes such a phenomenon if a faulty USB attachment is detected.
What I do know is that in testing five different virgin memory sticks only once has the Xbox I used, a v.1(0b), produced a, MS dash only(?) reformat option message. The reformatting worked but the device still didn't.
The others which haven't worked get the MS dash only(?) "damaged......" messsage or the equivalent flashed up message when using XBMC. You also get the "damaged..." message when a device that has been working but gets a "Copy Failed.." error, then goes missing from the dash and you try to reattach it without powering off first.
If you check your storage devices info in XBMC or it's File Manager that should show whether the stick has been reformatted to FATX. I don't know if any other dash File Manager confirms the FATX reformat but just because it has doesn't mean it will work.
Using UnleashX's Game Saves Manager won't show there's any memory device attached until you have something on it. Use UnleashX's File Explorer to see if it's there, usually it's either the L, J, or N drive depending which port you're using. If it's not or you see scrambled text alonside one drive that probably means it either hasn't been reformatted, failed during a copy or simply doesn't work.
IMHO it's best to use the MS dash to test these USB devices. The well designed graphics interface in Memory show you immediately what attachments are recognised and what aren't. If they go missing at any stage of the process you'll get instant visual confirmation and explanatory error message too.
This post has been edited by fallenangle: Feb 9 2011, 03:49 PM