My PC reboots whenever I try to run a slideshow with embedded mp4 videos

Linux Mint xfce Kernel: 5.15.0-79-generic x86_64 bits: 64 compiler: gcc v: 11.3.0 Desktop: Xfce 4.18.1
tk: Gtk 3.24.33 wm: xfwm dm: LightDM Distro: Linux Mint 21.2 Victoria base: Ubuntu 22.04 jammy

LibreOffice 7.3.7.2

I’ve just increased the desktop RAM to 16GB.
It has an AMD CPU with onboard graphics.
Hardware acceleration is OFF in LibreOffice

Presentation was created by s/o else in Powerpoint as pptx. I have converted it to .odp, and tried removing all the slides with videos, reducing their resolution, minimising the presentation, putting the videos back in (mp4 format) at the smaller resolution - but every time I try to run the presentation as a slide show, the PC reboots as soon as it gets to a slide with a video in.

Slideshow with videos taken out, runs fine.

Linking them instead of embedding, simply results in an unresponsive slide. (videos are in same folder as presentation).

Suggestions for troubleshooting welcome.

CPU:
Info: quad core model: AMD A8-5500 APU with Radeon HD Graphics bits: 64 type: MT MCP
arch: Piledriver rev: 1 cache: L1: 192 KiB L2: 4 MiB
Speed (MHz): avg: 2492 high: 3629 min/max: 1400/3200 boost: enabled cores: 1: 3549 2: 3629
3: 1396 4: 1396 bogomips: 25553
Flags: avx ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm
Graphics:
Device-1: AMD Trinity [Radeon HD 7560D] vendor: Micro-Star MSI driver: radeon v: kernel ports:
active: HDMI-A-1 empty: VGA-1 bus-ID: 00:01.0 chip-ID: 1002:9904
Display: x11 server: X.Org v: 1.21.1.4 compositor: xfwm v: 4.18.0 driver: X:
loaded: ati,radeon unloaded: fbdev,modesetting,vesa gpu: radeon display-ID: :0.0 screens: 1
Screen-1: 0 s-res: 1920x1080 s-dpi: 96
Monitor-1: HDMI-0 mapped: HDMI-A-1 model: HP 22xi res: 1920x1080 dpi: 102 diag: 551mm (21.7")
OpenGL: renderer: AMD ARUBA (DRM 2.50.0 / 5.15.0-79-generic LLVM 15.0.7)
v: 4.5 Mesa 23.0.4-0ubuntu1~22.04.1 direct render: Yes