Vista not loading properly and crashing

Hi

I have Vista x64 Ultimate and my computer has trouble starting it up. It always gets to the microsoft bar at the bottom as if it is going to load in and just as you think the vista sign is going to appear the monitor says there is no signal coming from the computer. The computer however is still on. Also the computer can crash randomly and again will show the same type of error reports. After a few attempts of rebooting I usually get in and it shows this problem:

Problem signatureProblem Event Name: BlueScreen
OS Version: 6.0.6001.2.1.0.256.1
Locale ID: 2057
Files that help describe the problemMini042108-02.dmp
sysdata.xml
Version.txt
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.
Extra information about the problemBCCode: d1
BCP1: FFFFFA6044C1C014
BCP2: 0000000000000002
BCP3: 0000000000000000
BCP4: FFFFFA60026FD43E
OS Version: 6_0_6001
Service Pack: 1_0
Product: 256_1

Problem signatureProblem Event Name: BlueScreen
OS Version: 6.0.6001.2.1.0.256.1
Locale ID: 2057
Files that help describe the problemMini042208-02.dmp
sysdata.xml
Version.txt
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.
Extra information about the problemBCCode: d1
BCP1: FFFFFA6044A1C00C
BCP2: 0000000000000002
BCP3: 0000000000000000
BCP4: FFFFFA600270043E
OS Version: 6_0_6001
Service Pack: 1_0
Product: 256_1

Problem signatureProblem Event Name: BlueScreen
OS Version: 6.0.6001.2.1.0.256.1
Locale ID: 2057
Files that help describe the problemMini042308-01.dmp
sysdata.xml
Version.txt
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.
Extra information about the problemBCCode: 50
BCP1: FFFFFA6044A1C00C
BCP2: 0000000000000000
BCP3: FFFFFA600270243E
BCP4: 0000000000000005
OS Version: 6_0_6001
Service Pack: 1_0
Product: 256_1

My System is:

Mb: Asus P5KC
cpu: Q6600
gx: GT8800 1gb ram
Mem: 4gb 800 mhz
hd: 500gb WD.

Thanks for reading and helping if you can!

If this is a new install, try taking one stick of RAM out and installing Vista with just 2 GB's, (if it's a new install go ahead and re format the disc, mkae sure to erase the old partition). If that works, then install SP1 and all the updates. If it still works, install the other 2 GB's. If it crashes again after you install the final 2 Gb's of RAM, manually input the CAS timings for your RAM. If it STILL crashes, slightly increase your RAM voltage.

i think your graphics driver is crashing - problems with 8800GT are common.

try using another graphics card and load latest nforce drivers from nvidia