OK, so I checked the Event Log after each of several blue screens. I've attached two of them. The blue screens occurred on 12/23 at 4:11pm, 12/24 at10:40pm,12/26 at 8:50pm and 9:06pm. Does anything pop out at you?
No negative (-) signs in the Device Manager.
I went out to the Microsoft website three days ago and loaded in all the updates they deemed necessary.
The processor and fan was full of dust, which I vacuumed, then blew out with a can of compressed air several days ago, so I don't think it is overheating.
Of all the dozen or so blue screens I've gotten just one time It showed:
Stop 0x.0000007f 0x,000000 0x.000000 0x.000000 0x.000000
Unexpected_Kernel_Mode_Trap
Beginning of Physical Memory Dump.
The computer runs very slowly at times, then picks up again.
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