Internal laptop HDD hangs/pauses the system momentarily while external USB doesn't

I have this peculiar problem that is like "disk thrashing on steroids", that is not technically thrashing since it's not the lack of RAM that is causing it and it can even happen on times of very low resources usage. However, it can hang the system for a few moments, up to 10 seconds sometimes if the application reads from it. It also does not appear to hang the OS itself, but the application that reads from it

That is:

* It happens on videos that are read from the internal HDD and not if they are read from an external USB drive. The video hangs as well as the audio and it resumes later. The rest of the OS does not appear hang completely, but applications such as browsers also "pause" momentarily.

* It happens on games provided they are not installed on an external USB drive.

* It happens on browsers and other applications that are installed on the internal HDD.


The computer in an HP DV7-5000 with the product number XE385EA. "Relative" models had an SATA problem and were eligible for replacement but, I heard that did not apply for the "HM55" chipset and it appears this model has the HM55 chipset so it's not that problem, even if I'm not completely sure they didn't screw up with that information.


I search for 'thrashing' and HM55 and I don't see anything definitive. Or with "pause" "hm55".

The problem appears also on completely different OSes (Linux, Win7 and Win8) so it appears closer to hardware, though you never know if both have the same software problem (unlikely).

Any idea what to do?

I wonder if a new internal disk would fix it or it's a controller problem.

The problem is that the laptop does not have a 2nd slot for a disk (not even connections) so one can't just add a second.

It occurs once every few minutes (7-10 minutes) for a few seconds and it was occurring since the beginning.

The disk led is on when it happens.

I have some limited programming knowledge: it reminds of an fread() hanging a single-loop app, but in a deeper hardware sense since it occurs on apps that provide for that.

The disk/controller from CrystalDiskInfo:

-- Controller Map ----------------------------------------------------------

+ Intel(R) Mobile Express Chipset SATA AHCI Controller [ATA]

- ST9500420AS

- hp CDDVDW TS-L633R

Hrm, I wonder if disabling the cd will fix it. I doubt it, but I may try it.