JB007:
O.K., I just fixed the problem, but in a quite stupid way:
I reuploaded all the cgi & pl files, and did the upgrade steps from the control panel, and it worked!!!
That means I still don't know what went wrong, but at least my UBB is working now.
Thanx for your kindness to answer my stupid question, and your hit counter v3.0 is working great on my UBB 5.47d now!!!