You need to do a backup if you want the contents of /home/tc/.X.d to survive a reboot.
The files in .X.d are sourced, so they do not need to be executable.
Your rdesktop script is a loop without exit.
.xsession will never finish running.
You need the script to exit so that the while loop in .xsession can complete.
Change it to
(
while x=0
do
sleep 5
/usr/local/bin/rdesktop -f ComputerName -d DomainName -u UserName
done
) &
This assumes /usr/local/bin/rdesktop does not immediately return,
but returns only when the rdesktop connection is terminated.
If it does return immediagtely, that script will not work as it will continuously start rdesktop.