Restoring saved state fails with mysterious error

[VM2VM]

I've been running a W7x64 guest on a W8.1x64 host for months without any problems, then suddenly trying to restore a saved state I was greeted with this mysterious error:
VERR_SSM_INTEGRITY_DECOMPRESSION like this:

Code: Select all

Failed to open a session for the virtual machine W7sp1u64 AS.
Failed to load unit 'pgm' (VERR_SSM_INTEGRITY_DECOMPRESSION).

Result Code: E_FAIL (0x80004005)
Component: Console
Interface: IConsole {8ab7c520-2442-4b66-8d74-4ff1e195d2b6}

I was looking at the bug tracking reports and this is in fact mentioned at least twice and as long as 3 years ago, and as recent as 10 months ago, but no resolution or action was taken.
https://www.virtualbox.org/ticket/8970
https://www.virtualbox.org/ticket/12607

Any ideas and help on what may be causing this would be appreciated. Or at least explain what the error means, so we can do our own trouble shooting.

PS. I'm running VB 4.3.14r95030

[mpack]

Right click | discard saved state.