getting 400 - Bad request after many request

[bhavin12300]

hi,
i have created one script in vb.net which request webpage from server and parse it.
initially Application making request to server and server response it too properly .But after making around 80 to 85 request i got following error in my code.

ex = {"The remote server returned an error: (400) Bad Request."}

But i am able to access all webpage more than 85 if i use browser.

i dont know why it is so.
can anyone let me know????

 

[bhavin12300]

atleast a bit information why i am getting this error??
pleaseeeeeeee