Amazing, but 2 ½ years later, exactly this is happening again!
Every three days or so, I get a BSOD for no reason when there is no activity on my machine for some hours. The listed driver cause is aswstmxp.sys.
My machine is almost the same XP SP3 machine as before - a Dell Optiplex 755 with 4GB RAM and the last BIOS update offered by Dell.
I say almost the same because about 6 weeks ago, my Dell Optiplex 755 Desktop stopped working (either power or motherboard) and so I bought a used same-model Dell Optiplex 755 Desktop without a hard drive and moved over my hard drive, RAM, DVD player unit, video card and fax modem card into the new used 755. (For those who know, msoobe.exe /a gives "Already activated", which is good.)
The only difference is that the CPU in this latest hybrid is slightly slower than the prior, but absolutely within the normal range for Dell Optiplex 755 DT.
And, per my posts above 2 ½ years ago, my XP was updated through April 2019 using the POS hack. (It's the same hard drive and XP as before.)
So why have these BSODs restarted?