I installed the Atheros WiFI driver (source:Toshiba website) on my laptop and the installation completed without any error although the driver didn't seem to work as WiFi was still unaccessible as if the driver was not installed so I attempted to install the driver again. This time, my PC bluescreened (well, it's more of a dark-cyan screen in W8) while the driver was being installed. The BS message was "IRQL NOT LESS OR EQUAL" and I've attached the minidumps to this post.

What can I try to get the driver to install successfully?

dumps.zip

I would first make sure to uninstall any Atheros drivers and software. If you are trying to install using a Setup application, try instead to point Device Manager to the location of the driver files. See if letting Windows manage the wireless does any better. I personally never install any application for wireless, just the driver.

the Atheros driver wsimdx.sys is very old (2009).

********************************************************************************                                                                             **                        Bugcheck Analysis                                    **                                                                             ********************************************************************************IRQL_NOT_LESS_OR_EQUAL (a)An attempt was made to access a pageable (or completely invalid) address at aninterrupt request level (IRQL) that is too high.  This is usuallycaused by drivers using improper addresses.If a kernel debugger is available get the stack backtrace.Arguments:Arg1: 0000000000000000, memory referencedArg2: 0000000000000002, IRQLArg3: 0000000000000000, bitfield :	bit 0 : value 0 = read operation, 1 = write operation	bit 3 : value 0 = not an execute operation, 1 = execute operation (only on chips which support this level of status)Arg4: fffff8005bad28cb, address which referenced memoryDebugging Details:------------------CURRENT_IRQL:  2FAULTING_IP: nt!KeSetEvent+43bfffff800`5bad28cb 488b00          mov     rax,qword ptr [rax]CUSTOMER_CRASH_COUNT:  1DEFAULT_BUCKET_ID:  WIN8_DRIVER_FAULTBUGCHECK_STR:  AVPROCESS_NAME:  SystemANALYSIS_VERSION: 6.3.9600.17029 (debuggers(dbg).140219-1702) amd64freSTACK_TEXT:  nt!KeBugCheckExnt!KiBugCheckDispatchnt!KiPageFaultnt!KeSetEventwsimdxIMAGE_NAME:  wsimdx.sysFAILURE_BUCKET_ID:  AV_wsimdx+9324FAILURE_ID_HASH_STRING:  km:av_wsimdx+9324      Loaded symbol image file: wsimdx.sys    Image path: \SystemRoot\system32\DRIVERS\wsimdx.sys    Image name: wsimdx.sys    Timestamp:        Tue Mar 17 07:19:55 2009 

Which model is it?

That is Wireless Intermediate Miniport Driver, Atheros Communications, Inc.

Update your drivers and you'll solve your problems:

http://www.atheros.cz/atheros-wireless-drivers.php

Let us know the results...