Things are getting worse. Now the system detects no USB hdd at all.
I do not think that I understand Your question, sorry.
A mountpoint is just a directory (folder) where you mount a partition.
If you mount the partition with the mount
command or automatically at boot via a line in /etc/fstab
the mountpoint has to exist before you or the system does the mounting.
On the other hand, if the partition does not have a line in /etc/fstab, HAL can handle the mounting, creating a mountpoint on the fly under /media.
Now, "uhelper=hal" is a relatively new option in /etc/fstab
and I don't know what it achieves. So I suspected that it also makes HAL create mountpoints on the fly. But this is just a guess. (I've googled for "uhelper" and found lots of bugs related to it but so far no explanation as to what one would need it for. Just give me some time.)
But if you create a permanent mountpoint, i.e. a directory where you always want to mount a certain partition, and then write the line in /etc/fstab so that it is mounted there, you don't need HAL. So my question actually meant: do the mountpoints exist all the time or are they created on the fly by the system?
You could try one of two things: either comment out the line for your USB drive in /etc/fstab, i.e put a hash (#) in front of it, and see if HAL can handle it.
Or check that the mountpoint folder exists when the partition is not mounted. If it doesn't, create it. (And possibly somewhere else than under /media, which has been more or less taken over by HAL.)
And then, possibly, simplify the line in /etc/fstab. Reduce the number of option to an absolute minimum. (See the line from my fstab.) If it doesn't work add one option at a time.