The column names you're using in the php array have the table part in them as well, this should not be the case. Change to the following.
$result = mysql_query("SELECT customer.custAutoID, products.prodID, products.prodDescrip, products.prodPrice
FROM customer
INNER JOIN products
ON products.prodID = customer.custProductID
",$db) OR DIE ( mysql_error() );
print ($num = mysql_num_rows($result));
while ($myrow = mysql_fetch_assoc($result)) {
$custAutoID = $myrow["custAutoID"];
$prodID = $myrow["prodID"];
$prodDescrip = $myrow["prodDescrip"];
$prodPrice = $myrow["prodPrice"];
//SHOW PRODUCTS IN THREE COLUMNS
print "<tr>";
print "<td>$prodID</td><td>$prodDescrip</td><td>$prodPrice</td>";
print "<tr>";
}
If you come accross the problem that you are selecting two columns with the same column name at some point you can use the as keyword as below.
select a.column as a_column, b.column as b_column from a,b where [condition]
HTH
Bubble