Shane
Thank you for the answer.
I have temperatures monitored permanently: GPU, HDs, MB and CPU. Usually, GPU is the higher one, 48 ou 49 C, close to the MB, then the HDs (they are two, 42 and 30 C), and the CPU is the lower one (32 to 54C, varying constantly), in an environment of 18C.
It seems to me this is not a temperature issue, because when it happens, the showed temperatures, although frozen as the rest, are not any higher than ever before.
As to memory and HD, I have the sidebar activated, and one of the gadgets there, is the CPU/RAM meter, and at the moment the freezing happens, they show quite normal too; yesterday RAM showed about 65%. About the HD I'm not so sure, CHKDSK do not indicate trouble, but in the past, things happened which I didn't understand, like analizes by Advanced SystemCare (from Iobit) saying there were problems, then I used to run CHKDSK and it seemed there was nothing wrong. Please tell how can I test both RAM and HD.
Nomad