BIg problems wih AN7 ............

I have big problems with my computer. My AN7 MB doesnt want to boot
somethimes:

Machine:
Abit AN7
AMD Atholon 2500+ Barton
2x256MB Kingmax Super RAM 3200
ATI Radeon 9200SE 64MB
Segate 120GB Serial ATA (two partition 10GB and 110GB)
Modem US Robotics v.90
Logic ATX2 400W
CD-RW
Cooler Spire Whisper Rock III
Windows XP Home Edition
Put together: 21.02.2004.

Temperature:
CPU no more than 50C idle
System no more than 38C
Power no more than 35C
In Bios all default CPU and RAM, CPU on 333 and RAM on 400(optimal), RAM
DIMM 1-2.
1.) All work fine till two days(1.3.) ago when WIndows reported fatal error
just after
complete boot. Something "Windows discovered fatal error with hardware....to
send report..see details....." Windows will be shut down to prevent damaging
system(something like that). And if I dont tuch anything then comes BLUES
SCREEN.......
2.) 02.03. - Same thing like previous problem. I decide to make reinstal
WinXP and formatdisc. First time formating goes well and copying too. After
first boot begins instalation and just one minute (where i must put language
and other) comes BLUE SCREEN with message:
DRIVER_IRQL_NOT_LESS_OR_EQUAL
TECHNICAL INFORMATION
STOP:0X000000D1(0X00000004,0X00000002,0X00000000,0XF8607697)
i8042prt.sys-ADDRESS F8607697 BASE AT F8606000, DATESTAMP 3b7de4b3
BEGINING DUMP OF PHISICAL MEMMORY..........
And I repeat instalation (just resert, no instalation from start no copying
files on disc)
and same thing BLUE SCREEN (same time same place in instalation). And I
again formated disc copying files on disc and same thing. I was thinking
that HDD was bad and I replace it with new one and there is same problem -
BLUE SCREEN, same massage same place and time. Next time when I try to boot
nothing happend. Nothing on monitor just black screen, procesor working and
fans. BUT ON MOTHER BOARD ON POST CODE stand number "C3", c3 means - expand
compressed bios code to DRAM. I dont know what that mean but I think it is
problem in memory. Then I resert again and same thing. I turn off power
complete and I wait 1 minute. Turn on and its OK, system boot. But same
thing with instalation - BLUE SCREEN. Go sleep 4am 03.03.

3.) 03.03. Get modem from MB. I was thinking about memory and I change
properties for memory. Now, By SPD, frequency 333MH like procesor. Change
location of RAM in DIMs. Now DIMM3 and DIMM2. Make again formating and
copying files on HDD and instalation goes OK. Thinking THANKS GOD.
Everything was nice. Work about 3 hours and turn off. When I come back for
about 2 hours and turn on computer I get again "C3" message on POST CODE and
constant beep from MB. No boot. Nothing on screen, procesor work, fans too.
Resert and system boots up. When Windows boots up I get again message that:
A problem has been detected and WIndows has been shut down to prevent damage
to your computer.... BLUE SCREEN. And again restart, next time everything is
OK. No "C3" and no message from Windows. I have 5 times restarts to see if
this thing will be again but everything is ok. Now I work on computer for 3
hours and its OK. Put back modem and everything is OK.

4.) This morning same thing like yesterday. Turn on comp and nithing
happens. Fans work, MB works but no boot. Back screen on monitor. I get
constantly beep from my MB. On POST CODE I get "90" - Complete iGuru initial
process, AWARD BIOS take over booting job". Beep still on. Take resert and
again nothing. Nothing on monitor. Then I turn off and on monitor take
another resert of comp and everything goes well this time, system boots up.
Then in WIndows I get BLUE SCREEN. This is message:
A problem has been detected and WIndows has been shut down to prevent damage
to your computer.
............
Technical info:
Stop: 0x0000008E(0xC0000005,0x805847F0,0xF7ce33d4,0x00000000)
Begining dump of phisycal memory.

And again restart and now this tim works good. Whats is going on with my
computer. Is it MB, RAM or power suply? I get same problem with turn on cold
computer. No boot. But when I turn off comp and turn on for 5 minutes I get
no problem. Please help me........

To complete data:
2500+ 166x11
FSB/DRAM ratio: 6/6 333MH
CPU core voltage 1.65V
DDR SDRAM VOltage 2.65V
NB CORE VOltage 1.55V

Voltage monitornig:
NB 1,64
CPU 1,69
DDR 2,69
DDR VTT 1,35