No maleware or viruses. and since my reported blue screen i didn't had another one, but I'm being cautious so I'm interesting in prevention.
By the way, i didn't do the chkdsk /r or chkdsk C: /f that was suggested, only chkdsk, and it told me that i had no bad sectors. should i do chkdsk /r? (what does it mean anyway?).
As suggested previously, typing CHKDSK /? would show you what all the switches (options) do.
CHKDSK won't even look for bad sectors unless you use the /R option. That's a low-level reliability scan which causes every sector to have its current data moved, replaced by a known pattern (0123456789... or whatever), and then subsequently read back again. If "results out" don't match the pattern that was written, obviously the sector is unreliable - "bad" - and it gets added to an NTFS metadata structure which keeps track of such unreliable locations on the disk surface so they can be avoided in the future.
Many HDDs nowadays have their own similar sector remapping features built into the firmware, and since that's underneath the OS file system a disk may be suffering from progressive substrate degradation issues even though it's not picked up by software scans (disk SMART status can pick that up though).