Encoding error for special characters...

Hi,
 I am creating a Website for mobile Devices using WML.
 I am using an Emulator  "Nokia Wap Toolkit2.0".
  If a user enters any of the two characters '&' or
'$' in edit box and try to POST the data from the deck
(an ASP page), the Emulator gives an 'Encoding Error'
with the following text :

The following error occured:
Bad name as variable reference.


How to overcome this problem?
Also, Is there any way to restrict the user to enter
any special character.

Thanks with regards,
Ashwini


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