Hi tcl_user5
When reporting this type of error, you should mention the architecture in addition to the version.
Looking back at some of your older posts I take it you are referring to x86_64.
I just checked the md5 of gcc against the .md5.txt file and they match.
Remove all gcc files:
rm -f /etc/sysconfig/tcedir/optional/gcc.tcz*
Try downloading compiletc again.