Scusa se rispondo solo ora, ma di giorno uso un altro Pc.
Sì quando ci clicco su il quadro nero si ingrandisce e appaiono neri anche i riquadri di qualsiasi cosa apra.
Mi permette solo di chiudere le finestre, ma poi mi rimane quel rettangolo centrale sul desktop (seconda figura).
Ti riporto il risultato del terminale:
System: Host: luca-Vecchio-Pc Kernel: 4.15.0-22-generic x86_64 bits: 64
Desktop: Gnome 3.28.1 Distro: Ubuntu 18.04 LTS
Machine: Device: desktop System: Packard Bell BV product: IXTREME J9403 v: PB81104506 serial: N/A
Mobo: Packard Bell BV model: Cuba MS-7301 v: 1.0 serial: N/A
BIOS: Phoenix v: W7301VP2.309 date: 02/17/2007
CPU: Dual core Intel Core2 6400 (-MCP-) cache: 2048 KB
clock speeds: max: 2133 MHz 1: 1595 MHz 2: 1595 MHz
Graphics: Card: Advanced Micro Devices [AMD/ATI] RV516 [Radeon X1600/X1650 Series]
Display Server: x11 (X.Org 1.19.6 )
drivers: ati,radeon (unloaded: modesetting,fbdev,vesa)
Resolution: 1366x768@59.79hz
OpenGL: renderer: ATI RV515 version: 2.1 Mesa 18.0.0-rc5
Audio: Card VIA VT8237A/VT8251 HDA Controller driver: snd_hda_intel
Sound: Advanced Linux Sound Architecture v: k4.15.0-22-generic
Network: Card: VIA VT6102/VT6103 [Rhine-II] driver: via-rhine
IF: enp0s18 state: up speed: 100 Mbps duplex: full mac: <filter>
Drives: HDD Total Size: 320.1GB (2.9% used)
ID-1: /dev/sda model: ST3320820AS size: 320.1GB
Partition: ID-1: / size: 293G used: 8.6G (4%) fs: ext4 dev: /dev/sda1
RAID: No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors: System Temperatures: cpu: 61.0C mobo: N/A
Fan Speeds (in rpm): cpu: N/A
Info: Processes: 194 Uptime: 14 min Memory: 1355.3/3000.4MB
Client: Shell (bash) inxi: 2.3.56