Erratic BSOD, usually while gaming; STOP screen says tcpip.sys

[littlebeast]

I'm running retail 64-bit Windows 7 Home Premium on a custom-built computer I made in summer of '09, the same install the whole time. Lately (last couple of weeks) I've been getting a BSOD after running a while, usually while gaming but sometimes when I've only been playing music.
I tried finding out the cause myself, to no avail; a BSOD interpreter told me that only ntoskrnl.exe and tcpip.sys were on the stack, but I'm not familiar enough with Windows's workings to really know what that means. Some more googling found a likely culprit, an outdated version of Asus's ACPI driver, but I was unable to find an updated version to download :/

So... yeah. BSOD. Diagnostic info attached. Please let me know if you have any leads.

 

[JaidynM]

You have avast! installed, is that correct? At least to test, uninstall it and install MSE (Microsoft Security Essentials) instead.
Microsoft Security Essentials - Free Antivirus for Windows

Make sure all Windows updates are installed.

Update to the latest service pack.

Download: System Update Readiness Tool for Windows 7 (KB947821) [February 2012]

Download: System Update Readiness Tool for Windows 7 for x64-based Systems (KB947821) [February 2012]

Steps to follow before you install Windows 7 SP1 and Windows Server 2008 R2 SP1 from the Microsoft Download Center

Download: Windows 7 and Windows Server 2008 R2 Service Pack 1 (KB976932)
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