Now this one is strange..
Try clearing templates cache first, also you may want to try to delete SKU variables in template rather then edit it out like I suggested earlier. To be more specific:
1) Go to
http://yourdomain.com/cleanup.php . If it didn't solve the case, try:
2) In your
/customer/main/product_details.tpl find :
Code:
<td class="property-name">{*{$lng.lbl_sku}*}</td>
<td class="property-value" id="product_code">{*{$product.productcode|escape}*}</td>
and replace with:
Code:
<td class="property-name"></td>
<td class="property-value" id="product_code"></td>
Please let me know if it worked for you