CHKDSK stuck on 10% for hours, neither CPU nor disk activity detected

Hello.

I have an external 250GB USB 2.0 drive that only has 129 very big files, each of them between 700MB and 8GB.

I tried to copy all this data to a new USB 3.0 drive using a commercial tool to compare and sync directories and files. 3 hours later, all but 9 of the files were copied. The tool reported CRC errors on those 9 files.

I run CHKDSK /F on the old drive and no errors were found. Then I tried the Error-checking tool from the properties window of the disk and checked both options to fix and scan. After some hours, I found it stuck in 10% with 149 files analyzed. It was strange that there was no disk activity and mmc.exe was using 6GB of RAM (the notebook has Win7 x64 with 8GB of RAM). Finally, I aborted the process and detached the disk.

I removed the SATA HDD from it's USB 2.0 case and connected it to a SATA-USB 3.0 adapter in a Win7 x86 PC, then run CHKDSK /R on it. In about an hour, it arrived to the same 149th file in stage 4/5. All the time it was at 10%, but Task Manager reported that CHKDSK took 1600MB of RAM (about 90% of current available RAM) during the first minute of the run and kept that. CPU percent for this process is 0%. The adapter's led flashed for some time at the beggining but then went off during the remaining process... it is still off but it is supposed that it should be on while in stand-by mode.

Questions:
- Has the memory issue a relationship with the size of the disk or the files?
- Are the CRC reported errors causing the stuck in CHKDSK.
- Should I wait or abort?

Update: While I was writing this post, CHKDSK released about 300MB of RAM, and some minutes later it released another 300MB. And the reads changed from 944.638 to 944.640... there are only 2 writes. So, again:
- Should I wait or abort?

As the backup tool was unable to copy them, I didn't try any other tool but CHKDSK to analyze the disk. But no, the files are not videos, so I can't try to play them...

Few hours after I posted this problem, CHKDSK aborted after many errors of this kind in stage 4:

Code:

The disk does not have enough space to replace bad clusters
detected in file 253 of name .
10 percent complete. (239 of 496 files processed)

The last message was:

Code:

Unspecified error occurred (6e74667363686b2e b34).

Of course, the disk had only about 8GB of free space, so after verifying which of the files were also stored in another disk, I removed them to try the CHKDSK again to see if it could recover the remaining bad ones. While doing that, I noticed that all those files had almost the same date, and were the last ones to be stored in that disk, so I think that there is a physical area in the drive that has problems. I didn't noticed that earlier because Windows Explorer and the sync tool were sorting them alphabetically by default in the GUI.

Anyway, I left another CHKDSK running at home, so I cannot say which model the drive is, but I can recall that it's a 2.5" 250GB Samsung drive I removed from a Dell notebook a couple of years ago and I initialized it to completely remove Windows and get all that space for my data. I think it was a low level format after placing it inside a generic USB 2.0 case for SATA drives.

I'll see what happened with this process in the evening. If I got the same errors, I'll try some forensic tools to do a surface scan.

Thank you!