the headers already sent error means that there is output to the page before the header function or session-start function is being called.
the error:
output started at /hermes/bosweb/web184/b1848/ipw.digitec2007/public_html/vehimax2010/Mem_vh_Updt.php:5
is telling you that the output is at line 4 or 5 of the Mem_vh_Updt.php page.
if you cannot find the problem, send a copy of the page so I can see the code at line 4 and 5.