CRM proxy generation error

Hi all,

   I am importing data from crm. I have generated proxy and used in console app. Its all working fine.

Suddenly I am getting error "Value cannot be null. Parameter name: IdentityProvider"

Now, I cant even generate the Xrm.cs using crmsvcutil with the same command I used initially. Same error "Value cannot be null"

What could be the issue?

I am able t login using web front end.