Right Boggin, let me do a summary:
Notebook HP Pavilion dv9890EP, Vista Home Premium 32 bit, bought 6 years ago, all original, 2 hard drives (1 with 2 partitions, C: is O.S., E: is a recovery partition; the other HD is single-partitioned, D:, data).
Problems (3):
(1) for a long time till last March 19th it used to freeze completely about once a fortnight, although temperatures and memory didn't show abnormal levels;
(2) since 2011 never completed both CHKDSK C: /r and CHKDSK D: /r, dropping out in the process.
(3) it was common (about once every 3 days) immediately after booting, having endless waits, the waiting circle spinning around; doing Ctrl+Alt+Del to call the task manager never worked because I could ever stop any process, task manager never responded.
Actions since last March 19th:
BIOS memory test concluded OK;
CHKDSK C: /f shows 0 KB in bad sectors;
HD Sentinel shows no problem;
after running CCleaner Drive Free Space Wiper on C:, CHKDSK C: /r still drops out;
after updating BIOS version, CHKDSK C: and D: /r still drop out.
In April 3rd, BSOD occured, and I recovered the notebook with a Macrium Reflect image.
Installed "Gsmartcontrol" and tried to run it, but BSOD happened, twice.
I found an old arquived CHKDSK C: log from September 2011 showing that back then there were 4 KB in bad sectors.
As I said before, nowadays it doesn't show any KBs in bad sectors.
This notebook didn't come with a Vista install disk, but after buying it I burnt recovery disks (2 DVDs) of the whole factory image, according to instructions (I believe at the time I had not SP2 installed yet). I never used them, I don't know whether they are usable after all these years. Would them be helpfull now?
As Shane said, there is the possibility of taking off the D: disk and plug it to a laptop with a SATA to USB adapter to try a CHKDSK /r; would it work with the C: disk as well?
Thank you all