Firefox Portable: all my installations got suddenly corrupted.

On my PC (running Windows 10 ver. 10.0.17763.107) I have many different installation on Firefox Portable (versions a little below the last one).
Each is aimed to a different activity and has different addons (not many, anyway).

Until yesteday, at late night, I have been working with most of them and they were perfectly working. This morning I'm experiencing precedentely unseen troubles on all of them:

- Firefox takes a long time to start
- It's irresponsive. When I type an url in the address bar and press enter nothing happens.
- Can't reach about:config neither
- When I try to start Firefox often I get a message "Another instance of Firefox is already running." despite the absence of entries in the Task Manager
- taskkill /T /F /FI "Imagename eq Firefox*" doesn't help that much.
- Brand new installation of Firefox Portable 86.0 has been operating accurately for a short while but now is malfunctioning.

It's really a trouble to me. I will be very grateful for any hints about diagnostic and recovery.

- Works fine: IronPortable 87.0.4450.0
- Works fine: MaxthonPortable 4.9.5.1000
- Works fine: Opera ver. 73.0.3856.344
- Works fine: OperaPortable 74.0.3911.160