Confirmed via [Ticket #1736] -- the podcast download location was on disconnect drive.

FYI: The issue will be fixed in 5.0.1.2411 as https://www.ventismedia.com/mantis/view.php?id=17977

As a workaround go to Options > Downloads/Podcasts and change
Download podcasts to: [....]
to another location where MM has write access.

Can you confirm that this works as workaround?

A developer will look at the log and reply in the Support Ticket.

When I try to update my podcasts the download list is populated but I receive an error message. The message reads something to the effect of: "The application throw an exception. The application called an interface that was marshalled for a different thread" The same issue appears in safe mode.
podcasts attempt to download from soundcloud, podomatic, omnycontent, feedburner, and a few RSS feeds direct from private websites. All fail.

Log report #723E62D6
Support Ticket #1736