Problem copying across network

I have 3 networked computers with hard drives that are shared. All are
running WinXP Sp3.

Computer A
Drive E and F

Computer B
Drive G and H

Computer C
Drive J and K

All computers can talk to each others drives with the exception that
Computer C, Drive J can not be readily accessed from other computers.
When I try to copy from Drive E or G or H to Drive J, a copy will
start and then just stop and lock up explorer on the computer that is
trying to copy. I can copy the exact same thing to Drive G or H or K
and have no problem.

I have tried disconnecting the drive and remapping it on Computer A &
B. No change.

Then I unshared Drive J on Computer C and then shared it again.
Remapped the Drive J on Computer A and Computer B. Still no better.

Does anyone have any thoughts?

Thanks in Advance.