Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))

Solution:This error occurred due to the improper shut down of the PC. The solution for this issue is to replace AjaxControlToolkit.dll in the Libraries folder of the IUSCRM project into the local AjaxControlToolKit.dll.

But in Net they posted lot of solutions, but that doesn’t work for me, but the above said solution if fine.