Well buddy, you are not alone. I have been fighting with this error code for 2 days now. I just played a different game and caused the same C0000005 code in it. I looked through at least 2 dozen supposedly helpful threads and none of them got me anywhere close to resolve this. One thing for sure, it is not ME3 related. Windows is the whole problem. There is a repair tool that claims to fix this thing, but them crows want $100 bucks for it. We have a few things in common btw. I use Win7 64 bit with 16gb ram as well. As for the audio I am on the Realtek optical atm but I also have a 24bit soundblaster card that makes no difference. I am going to try the game on 32 bits and let you know.
My stuff:
Win7 64bit
AMD 8150 (8core) CPU
16gb (Vengeance) ram
Military class II 990FXA-GD80 Mainboard
Sapphire Radeon 6950 HD
Realtek optical / Sounblaster Audigy4 (oldschool baby!)
Problem Event Name: APPCRASH
Application Name: MassEffect3.exe
Application Version: 1.1.5427.4
Application Timestamp: 4f46d052
Fault Module Name: MassEffect3.exe
Fault Module Version: 1.1.5427.4
Fault Module Timestamp: 4f46d052
Exception Code: c0000005
Exception Offset: 0005d077
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789
Steps taken so far:
1) updated all drivers
2) confirmed system integrity with diverse tools
3) reassured all hardware is installed and up to date
4) tried multiple save games (any other mission work anyway)
5) removed and added windows startup items
6) limited system services to the minimum
7) threw a pencil and punched the table top
8) altered Physx application
9) re-installed DirectX11
10) checked registry for unused or corrupted items/keys/strings/entries
11) checked and re-checked for viruses, malicious software etc.
12) stopped and closed all other programs
13) applied latest Windows update and patched everything to new
14) scratched my head in doubts and frustration
15) Started ME3 in admin mode
16) reproduced error code in Arma2, same text no results
17) checked game files and replaced (mission specific) suspicious ones
18) ran restoration utilities and confirmed system integrity (again)
19) altered memory allocation, maximized virtual memory
!20) Will try game in 32 bit mode (second windows 7 installation)!
I am currently unwilling to go through the installation process of origin and ME3 and wait till sometime next week....hope we can find a resolution soon, cuz otherwise we can't finish the game....