Windows 7 failure (0xc0000428)

I have an old computer, the configuration is: Pentium D Dual Core, 1 GB Ram, 250GB HD.

The error is intermittent: sometimes the computer freeze during Windows startup and sometimes freeze after 15 or 30 minutes of use.

First, it shows a BSOD (extremely fast) and after reboot, it shows this error (sorry, it's in portuguese, but the status code is 0xc0000428):

After one minute, the screen starts displaying this error:

Things I've done:

• Replaced the power supply unit;
• Replaced the surge protector;
• Replaced the VGA cable;
• Repaired Windows by CD (bootrec /fixMBR, bootrec /fixBoot, bootrec /rebuildBCD)
• Loaded without digital signature (pressing F8).

Anyone can help me?

Have you tried replacing the RAM?

This guy found doing so helpful, and intermittent issues including graphics buffer corruption sounds a lot like memory issues to me.