my PC freezes nearly everyday

Hello people,

I am currently experiencing some problems. My computer freezes and I do not know what to do anymore to trouble shoot it. I ran memtest86+ for 24h with no errors. I ran win mem diagnostics for 3 times in a row, everything good. I ran prime95 for 46h then I had to download something (University...) via Firefox and it froze (prime still running while downloading). I ran Furmark with no artifacts and I played BFBC2 for more than 3h without BSOD or freeze. I installed the latest drivers for my VIA sound chip, Realtek NIC, Catalyst 10.11, Updated all chipset drivers from AMD and uninstalled AHCI driver as I read that sometimes it can mess up with windows 7. I run my HDD in IDE with microsoft driver as I installed Windows without AHCI setting (ergo IDE setting) in BIOS and without loading the driver in the win7 installation. I reverted back to BIOS 1.80 from 1.90 as I never had problems with 1.80. Could it be that an "incompatible" BIOS could mess up with windows7? Maybe my particular setup isn't matching the 1.90 BIOS's programming? I have experienced 2 BSODs but they appeared after I forgot to set some things up (installed 2 drivers for 1 device once, forgot uninstalling 1st one/ had too low voltage on CPU). Note that my system is not overclocked.

Generally I can say that:

1. freezes occur in desktop applications (no games/directX stuff/OpenGL)
2. Most of the times (I think always, but not sure) Internet activity is there
3. freezes never give any messages after rebooting (eventviewer only shows 41 with 0x0)
4. freeze often occur while updating Battlefield Bad Company 2 or while I installed Win7 SDK 7.1, while updating the different programs at the end of installation (1GB update approx.)
5. freezes correlate with I-net browser usage. I think I almost always used some kind of I-net browser when it froze (even if it was just tzhe download box of Firefox)
6. freezes NEVER occur while gaming or benchmarking

I thought it could relate to my 7 year old 2nd HDD which I used until 2 days ago, but it still froze after disabling HDD in BIOS and Windows (actually not removed connector/plug). I thought I might be related to the NIC driver as I-net activity correlates positively. I have the newest rtl8111e driver now. Freezes are frequent (every 1-2 days) but are not reproducible. Freezes occur with and without CnQ, with and without minimum processor power above 5%. Freezes occur after 5h of usage or more most of the time. As I can game without freezes, I assume that the PSU is right as it pulls most power when gaming (crossfire setup with 2x170W TPD). My PC is also not overheating and there are no warnings in device manager. I checked my HDD with WD LifeDiag. all fine.

Well, if you need more information please tell me. I would be glad to hear from you as I am already troubleshooting this thing for 1 month.

Attached are the 2 BSOD minidumps. somehow windows doesn't let me access them... so I coudn't debug them/ write the log file...

do I have to debug the mnidumps on my machine?

should I check my PSU with multimeter? on what connectors? EPS/12vATX and main connector?

PS: now I could open them, but I lack the right symbols. where do I get those?