# --- ns_param libtdom [PATH-TO-libtdom0.x.x.so] # ---
to config.tcl fixed the problem for me.
Example: # --- ns_param libtdom /usr/local/aolserver45/lib/tdom0.8.1/libtdom0.8.1.so # ---
You also want to check if $LD_LIBRARY_PATH is set.