just had worse
partly off topic, partly on topic:
I wanted to give a shot to CIS 4 RC ...installed it (with AIS firewall uninstalled)...all worked fine, but got bored with it and decided to uninstall it a few hours later. Uninstalled CIS, rebooted >>> my new internal IP was an IANA IP
... I have no idea how it happened (well may be but too long to explain, and I'm not sure at all). I couldn't connect anymore to my router of course, changed IPV4 settings manually to what it should have been... connecting to the router was possible, but with errors, ie no real access (was still denied somehow).
On topic again: decided to go for a system restoration, and forgot to disable Avast self defense module
...did all the restore operations in safe mode (ie, rebooted in safe mode too), looked successful, rebooted in normal mode, login screen >>> login in...a nice light blue...and empty taskbar as a sign of welcome, and a completely black desktop. Logged out, back in, the same, rebooted in safe mode, uninstalled AIS completely, rebooted again in safe mode to make sure the uninstall process would be complete, rebooted then in normal mode: hallelujah
my desktop is back; time to reinstall AIS >>> see you later guys