Assuming your product  names start  with letters a-z, just add an
asterisk to the end of the code like this "[a-z]*" or the entire if
statement should look like this:

If aRow > [opening_stock].Column + 1 And strCurrentItem <> "" And
strCurrentItem Like "[a-z]*" Then


If any of your product names start with a number, then you have to
change the above pattern to reflect the product names.

The other option is to just eliminate the check completely like this
(assuming if the name field is not empty, then it must be legit):

If aRow > [opening_stock].Column + 1 And strCurrentItem <> "" Then