I carefully went through the checklist of what could be wrong:
Twice in the span of 48 hours I had the computer freeze (BSOD) while the crunching was going on.
Kernal Data Inpage Error
Possible causes for the error:
Bad Hard Drive sectors
File Access error due to virus
I ran the diagnosis for the desktop at boot which is a provided by Lenovo. It tests most everything mentioned above.
Everything seems fine except that the hard drive has now 11 bad sectors on it, which could be the result of an improper shutdown.
The desktop is an I7 4th generation and the HD is a Hitachi originally installed in the system. Since it is clear that the HD has had problems, I may have to give up on crunching until I replace a hard at a later stage. I was thinking of getting an SSD to replace the 1 TB HD. It will have to wait for some time as things are not very rosy at the moment and I must be a little careful in expenditure. I have everything backed up on a portable USB drive and I also have a laptop for back up just in case which I still use from time to time.
Anyway, I thought I should update the thread since I started it. Will be back to crunching hopefully soon, keeping my fingers crossed.