A potentially dangerous Request.Form value was detected from the client

i have 2 aspx files
1) 1.aspx - collects info from the user, stores into the DB.
2) 2.aspx - collects info from the DB and displays back to the user

in 2.aspx, i am encoding(htmlencode,urlencode.....) and displaying the info. so srcipt is displayed as text but not executed. -- expected result.
in 1.aspx, i am collecting info from textboxes and store in DB,i am getting below exception when clicked on save button.
   
"A potentially dangerous Request.Form value was detected from the client ...".

how do i fix it?
guys please dont tell me to turn off validaterequest.i want that to be turned ON, for security reasons.

also i want to validate the input before storing into the DB.so that my DB holds verified and trusted data(not malicious).


any help would be highly appreciated.
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