Tenho duas opções, tente primeiro um Server.HTMLEncode(texto), caso não funcione, tente as funções abaixo.
Function HTMLEspeciais(sString)
If (sString <> "") Then
sString = Replace(sString, "á", "á")
sString = Replace(sString, "â", "â")
sString = Replace(sString, "à", "à")
sString = Replace(sString, "ã", "ã")
sString = Replace(sString, "ç", "ç")
sString = Replace(sString, "é", "é")
sString = Replace(sString, "ê", "ê")
sString = Replace(sString, "í", "í")
sString = Replace(sString, "ó", "ó")
sString = Replace(sString, "ô", "ô")
sString = Replace(sString, "õ", "õ")
sString = Replace(sString, "ú", "ú")
sString = Replace(sString, "ü", "ü")
sString = Replace(sString, "Á", "Á")
sString = Replace(sString, "Â", "Â")
sString = Replace(sString, "À", "À")
sString = Replace(sString, "Ã", "Ã")
sString = Replace(sString, "Ç", "Ç")
sString = Replace(sString, "É", "É")
sString = Replace(sString, "Ê", "Ê")
sString = Replace(sString, "Í", "Í")
sString = Replace(sString, "Ó", "Ó")
sString = Replace(sString, "Ô", "Ô")
sString = Replace(sString, "Õ", "Õ")
sString = Replace(sString, "Ú", "Ú")
sString = Replace(sString, "Ü", "Ü")
sString = Replace(sString, """", """) '"
sString = Replace(sString, "<", "<") '<
sString = Replace(sString, ">", ">") '>
End If
HTMLEspeciais = sString
End Function
Function HTMLDecode(sText)
Dim I
sText = Replace(sText, """, Chr(34))
sText = Replace(sText, "<" , Chr(60))
sText = Replace(sText, ">" , Chr(62))
sText = Replace(sText, "&" , Chr(38))
sText = Replace(sText, " ", Chr(32))
For I = 1 to 255
sText = Replace(sText, "&#" & I & ";", Chr(I))
Next
HTMLDecode = sText
End Function
Espero poder ter ajudado