BSOD at random, inconsistent error codes

I've been getting BSODs at random over the last 5 months. They occur more frequently when playing games (e.g. StarCraft II, Heroes of Newerth), but occasionally occur just after startup or while idle as well.

Steps I have taken so far:
- installed new fans and case
- trialled a different graphics card (ATI Radeon 4670 1GB- now running 4870 512GB)
- bought new RAM and tried combinations of different slots (now running with all 8GB, new and old)
- done a clean install of Windows 7 Pro x64
- various other driver updates, etc.

but all to no avail. BSODs after each new try. Unfortunately I have lost the old dump files prior to the clean Win7 install two days ago, but the latest two dumps should be there. One of the regular occurrences when looking at the previous dump files in NirSoft BlueScreenView was the crash address "ntoskrnl.exe+7cc40".

System specs are up to date on my profile, and usual details attached.

I would really appreciate any advice on where to go from here. I am stumped.

Thanks in advance,
--Liam.

Your DMP doesn't appear to show any Anti Virus Program listed.
Please advise what you are using...

JMH: I have been using AVG Free 2012, but hadn't yet put it back on
after the clean install. It is up and running again now.

JaidynM: Thanks for the advice.

I am running the latest ASUS BIOS (BIOS 1005, 2009.07.31) for the
P5Q-SE motherboard.
I haven't ever overclocked the CPU or GPU.
I installed the ATK0110 driver. Then I tested the system (playing the game that makes it crash most often) and it still crashed.
I ran the sfc /scannow command. Upon consulting the log file, the following file caused
troubles: "WTVGOTHIC-R.ttc" Then I did two additional reboot+scans, neither of which found errors. After this, I tested the system again, and it still crashed.

Any other ideas? The new dump files are attached.

LiamN,
Your response noted re AV software..Thanks.

Jaidyn will return after his school day has completed to analyze your further DMP's.

Hmm... Windows update doesn't come up with any further updates.

USBs in use:
Logitech G110 keyboard
Razer lachesis 5600dpi mouse (although I just tested with an old optical mouse and it still crashed)
Logitech C500 webcam (although just tested with it unplugged and it still crashed)

Occasionally I would have my external HDD, ipod, etc. plugged in as well - but not at the moment.

As for AVG, the first two crashes were prior to AVG install, the second two crashes were post-AVG install... Should I still give Microsoft Security Essentials a whirl?

Thanks again to you and JMH for helping me so far. Much appreciated!

I could do that, but how would I stress the computer? It does occasionally BSOD after start-up, but more often it is while gaming...

As for incidents at the start of the BSOD's... I think it was after I started using the Logitech keyboard and Razer mouse. It crashes when gaming with a different mouse, but I'm not sure about the keyboard... I will test later tonight using an old keyboard instead...

My other option is to get a new mobo - after a quick search, an easy option would be to downgrade to a Gigabyte GA-G41M from my current ASUS P5Q-SE. I would drop to 4GB of ram (should be fine) and only a PCIE 1.0 x16 slot for my Radeon 4870 instead of a 2.0 slot.

How likely is that to work, do you think?