I have a multi boot system, two installs of XP and Windows 10.
Everything was working fine on an old Nforce 4 motherboard from 2006 with AMD X2 4200 CPU.
This board finally died just recently and was replaced with a used combo, ASRock 960GC-GS FX motherboard,
AMD FX 4300 CPU and 4 GB's of DDR3. Running regular BIOS with MBR (no uefi/gpt)
Windows 10 took the change of motherboard in it's stride and is working normally. For Windows XP I ran the repair install,
which over wrote the Win 10 boot loader with it's own. I continued testing XP like this for a couple of days. Everything was good.
Then I ran the Win 10 startup recovery and re-implemented Windows 10 boot loader - now the boot menu shows boot
Windows 10 or "earlier versions of Windows" - as it was originally.
Windows 10 still fine, but when I use XP, I'm getting these strange crashes in various programs, for example, avast anti-virus,
Firefox and Tmpgenc mpeg encoder. Looking at the summary for the Tmpgenc and Firefox dumps show "exception illegal instruction".
Here is one: https://crash-stats.mozilla.com/report/index/a7e4d91d-b28e-4c54-a8cd-a77492161031
This continued for a few days, while I'm scratching my head trying to figure out what is going on. Finally I run the XP recovery console
"fixboot" to restore the XP boot loader. Now when I use XP everything is back to normal. No more crashes anywhere.
These crashes only occur when XP boots through the Windows 10 boot loader.
Any idea what is going on ?