I can now confirm that sometimes when I execute a file it reports an "corrupt" error. And then if I execute it again, it works. So I would say there is something with the hard disk.
I also get sometimes a BSOD reporting a "bad_pool_header". I googled for it and it kind of confirm that there is something with the sata controller. See here.
In the link they say that a solution could be to update my chipset drivers but I'm not sure what that is. I have a Asus P7P55D Pro motherboard with an Intel i7 CPU. Could anyoe point me to the drivers that I should install/update ?
Edit, ok I will install the "Chipset" and "Sata" drivers that are in the "Dowanload" section of that link.