Why am I getting Paypal error messages on my shopping cart?

Please check for any unusual characters or letters in your product titles and your product prices. Remove anything that is not a letter or a number (e.g. & % ‘ etc) via the "add or update a shopping cart" option. Save and publish via Option 4 on the main Options Page and see if that helps. Also, when testing, be sure to empty your Paypal cart if there are any existing items in it.