Here's my whole form, if its of any consequence, but it worked fine before I added the textarea.
echo"
<form action=\"contract.php?action=amend_mworks&con=$_GET[con]\" name=\"frmEdit\" method=\"post\">
<br><b>List of Measured Works</b><br><br>
<table width=\"705\">
<tr>
<td width=\"30\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\"> <b>Item</b></td>
<td bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\"><b>Description</b></td>
<td width=\"80\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\" align=\"center\"> <b>Qty</b></td>
<td width=\"40\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\" align=\"center\"> <b>Unit</b></td>
<td width=\"50\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\" align=\"center\"><b>Rate</b></td>
<td width=\"50\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\" align=\"center\"><b>Ext</b></td>
<td width=\"50\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\" align=\"center\"><b>Claimed<br>(%)</b></td>
<td width=\"50\" bgcolor=\"#E8EBF0\" style=\"border:solid 1px #ccc\" align=\"center\"><b>Claimed<br>To Date</b></td>
</tr>
";
// Display basic row of info for measured works (i.e. item, qty etc)
$get_mworks = mysql_query("
SELECT mworks_id as mid,
mworks_item as item,
mworks_detail as detail,
mworks_qty as qty,
mworks_unit as unit,
mworks_percent as percent,
mworks_qty * mworks_rate as ext,
(mworks_percent / 100) * (mworks_rate * mworks_qty) as ctd,
mworks_rate as rate
FROM val_mworks
WHERE mworks_con = '".$_GET["con"]."'
ORDER by mworks_id ASC
",$objConnect);
while($data = mysql_fetch_array($get_mworks))
{
echo"
<tr>
<td valign=\"middle\">$data[item]</td>
<td valign=\"middle\"><textarea id=\"detail[]\" name=\"detail[]\" rows=\"7\" cols=\"35\" wrap=\"hard\">$data[detail]</textarea></td>
<td align=\"center\" valign=\"middle\"><input type=\"text\" style=\"background-color: transparent; border-style: solid; border-width: 0px 0px 1px 0px; border-color: #001947\" name=\"qty[]\" size=\"7\" value=\"$data[qty]\" id=\"qty\"></td>
<td align=\"center\" valign=\"middle\">$data[unit]</td>
<td align=\"center\" valign=\"middle\">";
$rate = number_format($data['rate'],2);
// Calculate and display measured works ext, and percentage and amount already claimed
echo"
£$rate</td>
<td valign=\"middle\" align=\"center\">";
$ext = number_format($data['ext'],2);
echo"£$ext</td>
<td align=\"center\" valign=\"middle\"><input type=\"text\" style=\"background-color: transparent; border-style: solid; border-width: 0px 0px 1px 0px; border-color: #001947\" name=\"percent[]\" size=\"5\" value=\"$data[percent]\" id=\"percent\"></td>
<td align=\"center\" valign=\"middle\"><input type=\"hidden\" name=\"mid[]\" value=\"$data[mid]\" id=\"mid\">";
$ctd = number_format($data['ctd'],2);
echo"£$ctd</td>
</tr>";
}
echo"
</table>
<br>
<input type=\"submit\" name=\"submit\" value=\"Save Changes to Measured Works\"></form>";