Calibre 32 bit and 64 bit versions both work fine on both 32 bit and 64 bit machines with Windows 8. Despite the "guess" made in the previous post, Windows 8 OS is pretty much the same for desktop applications as Windows 7 i.e. it is definitely not "more designed for a tablet than a PC".
I cannot comment on any issues that may be arising from Calibre itself as I am just not familiar with in any way other than as a user. But looking from the OS side (of which I am no great wiz at either
), should the issue lie there, my first shot from the error log is that you have a permissions problem.
Each time Calibre is run it constructs a temporary folder with name of format C:\Users\Tashfin\AppData\Local\Temp\calibre_0.9.18 _tmp_* (where * is random alpha/numeric) - it should be automatically deleted again when Calibre is closed and it appears that Calibre may be having difficulties putting its temporary session files into that folder.
I would first check to see that that folder is being deleted automatically each time Calibre is closed - if not manually delete it with Calibre closed and see if that solves the problem.
If not then check that for that folder, when it is created during a Calibre session, you (as user) and SYSTEM should have Full Control, and that should be so for all its subfolders and files as well (under Advanced in the Security tab of the folder's properties).
However, I qualify that by if permissions are the problem, then I would have expected that you may have had similar issues with other applications that use the ...\Temp subfolder as its permissions of full control should propagate to its subfolders.