Problem with chkdsk - was sudden change in startup time

I have been working through some of the ideas suggested on this news group
in connection with my sudden change in startup time but still no joy. I have
tried defragging the disks to see if it could be a disk problem given the cd
icon that appears after the welcome screen appears. I have also checked to
see if the "dirty" bit on the disc is set causing Autochk to run at boot but
it is not set. Whether Autochk is running or not I do not know.

So the next thing I tried was to run Chkdsk from the popup dyalog box with
both disk options checked. I then shutdown the machine and restarted to
allow Chkdsk to run on startup. Well it did but only as far as the intial
boot that is when I assume Chkdsk kicked in but it went no further at least
in the two hours I left the machine alone. The disk light was on all the
time but the screen did not come on. I tried running Chkdsk on another
machine and a pale blue screen appeared and told me what Chkdsk was doing.

For those that understand these things the hardware set up is:

IDE Controller NVIDIA nForce4 Parallel ATA Controller
SCSI/RAID Controller NVIDIA nForce(tm) RAID Class Controller
SCSI/RAID Controller NVIDIA nForce4 Serial ATA RAID Controller
SCSI/RAID Controller NVIDIA nForce4 Serial ATA RAID Controller
SCSI/RAID Controller WDC WD2500JS-00MHB0
SCSI/RAID Controller WDC WD2500JS-00MHB0
Disk Drive NVIDIA STRIPE 465.77G (465 GB)

Any ideas welcome.

Graham.