On Sunday, 26 August 2018 09:07:23 BST Hervé Guillemet wrote: > Hello, > > After a recent system update I get this annoying strange behavior: when > scrolling in a firefox or thunderbird window with the mouse wheel, the > full X interface freezes for some seconds, then a system beep is emitted > and the interface unfreezes, but most of the time the mouse cursor > becomes invisible. If it is a BIOS beep, rather than a desktop/application sound, then you have some hardware problem. The recent update may have implemented some hardware acceleration rendering on the browser and this is putting pressure on your GPU, RAM, PSU. A single beep points to RAM, but I don't know all OEM's BIOS codes. I'd start by opening the cover and reseating your RAM modules. Oxidisation may have increase contact resistance. Usually pulling them out and pushing them back in cleans them enough to restore a good electrical contact. While you're there try removing all the dust from CPU, GPU, PSU coolers and air ducts using a vacuum cleaner (carefully) or a compressed air can. Keep holding the chassis at all times with one hand or use an earthing strap, some vacuum cleaners I've tried have a terrible problem with creating static electricity and a discharge could blow your MoBo chipset. Finally, reseat any SATA/IDE cables. Their contacts can also corrode with time and if the browser is caching pages on disk while the freeze occurs it might cause a problem, although unlikely to get a BIOS beep from it. You wouldn't be able to boot with a hard disk failure beep code going off, if this was your problem. > I must restart X to get it back. This sounds like a Xorg drivers problem, but if Xorg has partially crashed due to RAM or power problems, then this cursor problem will go away after you address the hardware issue. > Scrolling with scrollbars or arrow keys works. > Scrolling with wheels in others apps like terminals works too. > No useful message in syslog, dmesg or console. What does /var/log/Xorg.0.log reveal? -- Regards, Mick