windows xp logon error

hi, i don't know what happened, but i was watching a video and half way through, it crashed, saying some cyclic redundancy error message or something. and then shortly after that, i got the blue screen of death. i paid no attention to it and rebooted my computer. after i rebooted my
computer, it would load up to the windows logon screen
(where you select the user name and type in password)
and then freeze. all i get is a blue screen with the
windows logo after rebooting several more times, i
finally got the blue screen with this error:

STOP: c000021a {fatal system error}
The Windows Logon Process system process terminated
unexpectedly with a status of 0xc0000006 (0x00000000
0x00000000)
The system has been shut down.

i ran chkdsk to attempt to repair any possible errors,
and then rebooted. after that, i booted windows normally
and a blue screen came up and mentioned something about
checking my disks (another form of chkdsk?). well, it
went through and start repairing files and inserting
files into other files (it actually said inserting file
into xxx). but after that, it still froze up at the
windows logon. i ran chkdsk yet again, but it was weird.
after it got to about 70%, it reseted back to 50% and
took abou 2 hrs to go up 1%. I left it on overnight and
it was finished the next day. I again attempted to boot
into windows through safe mode, but it froze, so i turned
off my computer, and tried booting into windows normally.
this time, i got a little panda icon down in the corner
of my windows logon screen (i have panda antivirus and
for some reason it's always there at logon). the green
light was still on, indicating my hdd was working (unlike
before). after a few minutes, my hdd started making
whirring noises like it was struggling, that's when i
shut it off and I havne't done anything else since then.

so now i can't login to windows or safetymode, so i can't
use system restore.



Can anyone please help me? thanks