Your Western Digital hard drive is disappearing as shown in your lsusb output (Port 3):

lsusb -t output:

/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc_otg/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/3p, 480M
        |__ Port 1: Dev 3, If 0, Class=vend., Driver=smsc95xx, 480M
        |__ Port 3: Dev 4, If 0, Class=stor., Driver=usb-storage, 480M

lsusb -t output after a while:

/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc_otg/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/3p, 480M
        |__ Port 1: Dev 3, If 0, Class=vend., Driver=smsc95xx, 480M


I recommend that you copy all of your data off of this drive to another hard drive before it fails completely. 

It is possible that it could be the USB connection on the Pi instead of the drive.  Does the drive behave like this on a different computer system?

Again, I strongly recommend that you backup any irreplaceable data on this drive before it fails completely.  If you have another USB drive I recommend using rsync.  I use the following command to backup one external hard drive to a 2nd device on my Pi where /media/USBHDD1 is the mount point of the 1st drive and /media/USBHDD2 is the mount point of the 2nd drive.  rsync can recover from an interrupted copy in case your drive disappears while performing the copy.  You should be able to just power cycle failed drive and perform the copy command again.  rsync should pick up where it left off.

rsync -av --delete /media/USBHDD1/* /media/USBHDD2/


Suddenly got an I/O error from my external HDD
I'm trying to create an inventory sheet for our lab, and as such I need a large blank table. Is there a better way to do this then copy and pasting \midrule&amp;&amp;&amp;\\ over and over again?

I'd like to look like this, but automatically repeat the blank cells until the page is full:

%Page layout here
\documentclass[letterpaper, 12pt,twocolumn]{article}
\usepackage[left= 2 cm, right=2 cm, top = 2 cm, bottom = 2 cm]{geometry}

%Font stuff here
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}

%Goddamn tables.
\usepackage{booktabs} %Makes the pretty table based on wikibooks example

\begin{document}

\centering
{\large
\begin{tabular}{c|c|c|c}
\toprule
Date &amp; User &amp; Amount Used &amp; Procedure\\
\phantom{2015-3-17} &amp; \phantom{NAME} &amp; (mg) &amp;  \phantom{XXX3-33}\\
\midrule
&amp;&amp;&amp;\\
\midrule
&amp;&amp;&amp;\\
\midrule&amp;&amp;&amp;\\
\midrule&amp;&amp;&amp;\\
\midrule&amp;&amp;&amp;\\
\bottomrule
\end{tabular}
}
\end{document}


Note: I'm just using Booktabs to add the midrule, that can be dropped. This is just going on a clipboard on the wall, it can be ugly as you want. I'm just sick of fighting with Word's hellish layout tools. 

Edit: There is this answer that places blank lines in the middle, but I don't understand the code nearly enough to modify it to fill to the end of the page. 
