No, both ASP's did not reply to my email. I'll send out new emails, to more ASP's. Hopefully, they can solve it.
However, I did figure something. I have been experimenting with different drivers for REALTEK Lan. I've downloaded different drivers for different models (8100cl to 8139xx) and tried some of them, to see if it would solve the problem.
I finally ended up with "motherboard_driver_lan_realtek_8111" RTSNT.696 released 2008/06/16.
It did change something, my laptop is now crashing even more often...

As soon as I load uTorrent it will crash, and on other network operations it will crash more often too.
Although I'm not happy with this driver, it does point out that the problem might be in the REALTEK lan driver. So I'll try some more drivers, but I don't expect to find the 'perfect' one which solves all the crashes.
I'll keep you posted.