chkdsk problem

[#1]

I appear to be having a problem with my hard drive, where occasionally the pc goes into a loop when it boots up (see my post on the Hardware section). Therefore, I am trying to fit a new drive. To get my software across to the new drive, I installed it in an external USB caddy, then tried running a Ghost Image (Semantic software I think) from the DVD Drive on my pc. Trouble is, each time I try this, after copying about 400 sectors it gets stuck and complains that there are a number of bad sectors (about 64).
To try to fix this, I ran 'chdsk'. This was in Read-only mode, so it only looked for problems, it didn't fix them. It didn't report any problems, so I ran 'chkdsk /r'. I had to restart the pc to get chkdsk started. It went through the first three stages without complaint, but at 2% into Stage 4, the pc just froze. It didn't complain, it didn't report a problem, it just froze.
I had to power down the pc at the main switch, and when the pc restarted, I had to cancel 'chkdsk'. The pc is still working reasonably reliably, but I still want to change the drive just in case. Therefore, if anyone has any ideas what I can do to fix this 'chkdsk' problem, I would be grateful to hear them.
Thanks in advance

[#2]

Which version of the operating system are you running?

[#3]

I am using XP Pro. As far as I can tell, it is up-to-date. I usually upate as an when I get the message that updates are available.
I am still occasionally getting the bootup problem, and usually using my XP CD and going into Repair, then running Chkdsk c: /r eventually gets the pc into a state where it will boot up, but running chkdsk in XP Repair still has its funnies. In this case, chkdsk seems to go through to 50%, pauses for several seconds, then shoots on to 75%, but then jumps back to 50% where it sticks
Very strange

[#4]

Too late! Now I cannot even access the hard drive with it installed as an external drive connected through a USB port. Judging by the sound, the drive spins up but I am unable to access any of it, so now I am looking for a way to get my pc to see this drive as an external drive.
Therefore, I am moving this problem to the Windows Hardware section of the forum.