A potentially dangerous Request.Form value was detected from

Question

Hi Every one,

 

In textboxi need to accept all values but when enter "&#"  it will get "

 

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

 

may i know the reason for getting error and how can i handle this error using java scriptforrestrict this serice of characters 

 

Plese give me replay ASAP