Getting "access to the path \\myServer\c$\UploadFileFolder" is denied

Using asp.net/vb.net 2005
I am trying to upload a file using FileUpload control to the "UploadFileFolder" folder but getting an error:
<ERROR>
Server Error...."Access to path \\myServer\c$\UploadFileFolder" is denied. Description: an unhandled exception occurred during the execution of
the current web request.  Exception Details: System.UnauthorizedAccessException.
Access to path...is denied
ASP.NET is not authorized to access the requested resource.
Consider granting access rights to the resource to the ASP.NET request identity.
ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or
Network Service on IIS 6)
that is used if the application is not impersonating. If the application is
impersonating via
<identity impersonate="true"/>, the identity will be the anonymous user
(typically IUSR_MACHINENAME)
or the authenticated request user.
</ERR ...