Bonjour LeFrettchen, thank you for helping me.
Does this solution fix the problem once and for all ?
Yes
What is your mouse ?
Sysgration ASUS ROG Laser Gaming Mouse GX1000
Did you made a quick search about your mouse ?
I just did, but I am not sure what to google...
Does the problems occurs just like that ?
When I start applications like firefox, thunderbird, or even some settings stuff
Or did you try some special commands/hacks ?
No
Something like
wsmoused(8) ?
I don't even know what that is, not yet I guess 
En gros, en mode normal ou en bidouillant ?
j'l'avais pas vu venir celle la, tu m'as bien eu. No bidouille, only in a very casual use.
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Here the dmesg output right after the issue occurs, and after I moved the mouse from one port to another:
HTML Code:
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wsdisplay0 at inteldrm0 mux 1: console (std, vt100 emulation)
wsdisplay0: screen 1-5 added (std, vt100 emulation)
"Intel Q45 Video" rev 0x03 at pci0 dev 2 function 1 not configured
"Intel Q45 HECI" rev 0x03 at pci0 dev 3 function 0 not configured
pciide0 at pci0 dev 3 function 2 "Intel Q45 PT IDER" rev 0x03: DMA (unsupported), channel 0 wired to native-PCI, channel 1 wired to native-PCI
pciide0: using apic 1 int 18 for native-PCI interrupt
pciide0: channel 0 ignored (not responding; disabled or no drives?)
pciide0: channel 1 ignored (not responding; disabled or no drives?)
puc0 at pci0 dev 3 function 3 "Intel Q45 KT" rev 0x03: ports: 1 com
com4 at puc0 port 0 apic 1 int 17: ns16550a, 16 byte fifo
com4: probed fifo depth: 0 bytes
em0 at pci0 dev 25 function 0 "Intel ICH10 D BM LM" rev 0x02: msi, address 00:24:81:eb:d2:2a
uhci0 at pci0 dev 26 function 0 "Intel 82801JD USB" rev 0x02: apic 1 int 20
uhci1 at pci0 dev 26 function 1 "Intel 82801JD USB" rev 0x02: apic 1 int 21
uhci2 at pci0 dev 26 function 2 "Intel 82801JD USB" rev 0x02: apic 1 int 22
ehci0 at pci0 dev 26 function 7 "Intel 82801JD USB" rev 0x02: apic 1 int 22
usb0 at ehci0: USB revision 2.0
uhub0 at usb0 configuration 1 interface 0 "Intel EHCI root hub" rev 2.00/1.00 addr 1
azalia0 at pci0 dev 27 function 0 "Intel 82801JD HD Audio" rev 0x02: msi
azalia0: codecs: Analog Devices AD1884A
audio0 at azalia0
ppb0 at pci0 dev 28 function 0 "Intel 82801JD PCIE" rev 0x02: msi
pci1 at ppb0 bus 32
ppb1 at pci0 dev 28 function 4 "Intel 82801JD PCIE" rev 0x02: msi
pci2 at ppb1 bus 48
uhci3 at pci0 dev 29 function 0 "Intel 82801JD USB" rev 0x02: apic 1 int 20
uhci4 at pci0 dev 29 function 1 "Intel 82801JD USB" rev 0x02: apic 1 int 21
uhci5 at pci0 dev 29 function 2 "Intel 82801JD USB" rev 0x02: apic 1 int 22
ehci1 at pci0 dev 29 function 7 "Intel 82801JD USB" rev 0x02: apic 1 int 20
usb1 at ehci1: USB revision 2.0
uhub1 at usb1 configuration 1 interface 0 "Intel EHCI root hub" rev 2.00/1.00 addr 1
ppb2 at pci0 dev 30 function 0 "Intel 82801BA Hub-to-PCI" rev 0xa2
pci3 at ppb2 bus 7
pcib0 at pci0 dev 31 function 0 "Intel 82801JDO LPC" rev 0x02
pciide1 at pci0 dev 31 function 2 "Intel 82801JD SATA" rev 0x02: DMA, channel 0 configured to native-PCI, channel 1 configured to native-PCI
pciide1: using apic 1 int 18 for native-PCI interrupt
wd0 at pciide1 channel 0 drive 0: <ST9500325AS>
wd0: 16-sector PIO, LBA48, 476940MB, 976773168 sectors
wd1 at pciide1 channel 0 drive 1: <WDC WD20EZRZ-00Z5HB0>
wd1: 16-sector PIO, LBA48, 1907729MB, 3907029168 sectors
wd0(pciide1:0:0): using PIO mode 4, Ultra-DMA mode 6
wd1(pciide1:0:1): using PIO mode 4, Ultra-DMA mode 6
atapiscsi0 at pciide1 channel 1 drive 0
scsibus1 at atapiscsi0: 2 targets
cd0 at scsibus1 targ 0 lun 0: <HL-DT-ST, DVD-RAM GH40L, RB02> ATAPI 5/cdrom removable
cd0(pciide1:1:0): using PIO mode 4, Ultra-DMA mode 5
pciide2 at pci0 dev 31 function 5 "Intel 82801JD SATA" rev 0x02: DMA, channel 0 wired to native-PCI, channel 1 wired to native-PCI
pciide2: using apic 1 int 18 for native-PCI interrupt
usb2 at uhci0: USB revision 1.0
uhub2 at usb2 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb3 at uhci1: USB revision 1.0
uhub3 at usb3 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb4 at uhci2: USB revision 1.0
uhub4 at usb4 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb5 at uhci3: USB revision 1.0
uhub5 at usb5 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb6 at uhci4: USB revision 1.0
uhub6 at usb6 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb7 at uhci5: USB revision 1.0
uhub7 at usb7 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
isa0 at pcib0
isadma0 at isa0
fdc0 at isa0 port 0x3f0/6 irq 6 drq 2
com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo
pckbc0 at isa0 port 0x60/5 irq 1 irq 12
pckbd0 at pckbc0 (kbd slot)
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
lpt0 at isa0 port 0x378/4 irq 7
uhidev0 at uhub3 port 1 configuration 1 interface 0 "Sysgration ASUS ROG Laser Gaming Mouse GX1000" rev 1.10/1.04 addr 2
uhidev0: iclass 3/1
ums0 at uhidev0: 16 buttons, Z dir
wsmouse0 at ums0 mux 0
uhidev1 at uhub3 port 1 configuration 1 interface 1 "Sysgration ASUS ROG Laser Gaming Mouse GX1000" rev 1.10/1.04 addr 2
uhidev1: iclass 3/1
ukbd0 at uhidev1: 8 variable keys, 6 key codes
wskbd1 at ukbd0 mux 1
wskbd1: connecting to wsdisplay0
uhidev2 at uhub3 port 1 configuration 1 interface 2 "Sysgration ASUS ROG Laser Gaming Mouse GX1000" rev 1.10/1.04 addr 2
uhidev2: iclass 3/1
uhid0 at uhidev2: input=4, output=0, feature=0
vscsi0 at root
scsibus2 at vscsi0: 256 targets
softraid0 at root
scsibus3 at softraid0: 256 targets
root on wd0a (76e4ecc7f2cfaae0.a) swap on wd0b dump on wd0b
error: [drm:pid32623:intel_pipe_update_start] *ERROR* Potential atomic update failure on pipe A
wsmouse0 detached
ums0 detached
uhidev0 detached
wskbd1: disconnecting from wsdisplay0
wskbd1 detached
ukbd0 detached
uhidev1 detached
uhid0 detached
uhidev2 detached
uhidev0 at uhub3 port 2 configuration 1 interface 0 "Sysgration ASUS ROG Laser Gaming Mouse GX1000" rev 1.10/1.04 addr 2
uhidev0: iclass 3/1
ums0 at uhidev0: 16 buttons, Z dir
wsmouse0 at ums0 mux 0
uhidev1 at uhub3 port 2 configuration 1 interface 1 "Sysgration ASUS ROG Laser Gaming Mouse GX1000" rev 1.10/1.04 addr 2
uhidev1: iclass 3/1
ukbd0 at uhidev1: 8 variable keys, 6 key codes
wskbd1 at ukbd0 mux 1
wskbd1: connecting to wsdisplay0
uhidev2 at uhub3 port 2 configuration 1 interface 2 "Sysgration ASUS ROG Laser Gaming Mouse GX1000" rev 1.10/1.04 addr 2
uhidev2: iclass 3/1
uhid0 at uhidev2: input=4, output=0, feature=0
We have a clue:
error: [drm: pid32623:intel_pipe_update_start] *ERROR* Potential atomic update failure on pipe A
I am going to make some inquiries, awesome!
Have a nice day everybody.