That's annoying.
My desktop system is a Win7 Pro box with a quad core Xeon CPU and 8GB RAM. Win7 and Ubuntu dual boot from an SSD.
Win10 finally became available for download, and wanted me to start upgrading. As it happens, I already downloaded the ISO file and created a USB stick installer. I simply hadn't gotten to it.
But
something about the process hosed my Windows state. The entire machine appeared hung, and it wouldn't even power cycle from the front panel power button. I had to reach behind and disconnect the power cord, than plug it back in.
It did provide an opportunity to update Ubuntu with the latest batch of critical updates, which I did before booting back into Win7.
All seems normal. The annoyance is my browser setup.
With 8GB RAM, I have enough to play a bit. I found a 64 bit ramdisk driver that works in Win7, and there's a 1GB ramdisk seen as Z: with an NTFS filesystem. I'm set up to have Firefox's browser cache and profile on the ramdisk. A startup script loads the FF profile to the ramdisk from a zip archive on the hard drive, A shutdown script zips it back to catch profile changes made in that session. (I have fast broadband and don't bother preserving cache.)
The profile in the zip archive hadn't been updated in a bit, so when Windows came back up and I ran Firefox, it was a time machine trip to days back. Various updates made since the last time the zip was updated vanished.
It's not a disaster, but it is a reminder that I need to update the zip file regularly...
It
is the first time I've seen this machine so jammed up it won't power off from the front panel. That's...different.

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Dennis