Infection (according to ClamXav) in "/private/var/db/PreviousSystemLogs.cpgz"? How do I fix this? What does it mean?

I'm not sure what do to, I am very good at OS X and Mac Software, but I've never gotten an infection notice by ClamXav and let alone in /private/var.

EDIT: Also, infection name: Html.Exploit.CVE_2012_1537_1.
I wouldn’t worry. You can safely ignore it. After looking up the CVE ID, the malware in question is only a threat to one running Windows; there’s no threat in an OS X environment. Here’s the description of the ID on CVE’s database:


  Heap-based buffer overflow in DirectPlay in DirectX 9.0 through 11.1 in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, Windows 7 Gold and SP1, Windows 8, and Windows Server 2012 allows remote attackers to execute arbitrary code via a crafted Office document, aka "DirectPlay Heap Overflow Vulnerability.


See also the accompanying list of the specific platforms affected. 

Even good, non intrusive AV-software such as ClamXav is prone to false positives. If you want, you can still safely remove that file. It’s just an archived log. I would just tell ClamXav to ignore it.