ok, 'Error A: Later version already installed' when run in GDebi Installer.
cd ~
wget http://launchpadlibrarian.net/283032290/linux-libc-dev_4.4.0-38.57_i386.deb
sudo dpkg -i --force-downgrade linux-libc-dev_4.4.0-38.57_i386.deb

Well as I expected, all is well again after reverting back.
At 1st boot up this morning and a reboot, no issue whatsoever.
Deffo a kernel issue (32bit anyway) as everything is back to what it was 2 days ago.
Thereagain, maybe it's just the 32bit version as most are on 64bit versions of PM7..who knows?

Time for a Timeshift snapshot me thinks..

In my instance, a cautious approach is required for future level 5 kernel updates (ignore in mintupdate!)