Web service autentication problem when call another web service

[Redhot]

Hello,

- I have 2 .net 2.0/3.5 web services in one web server: WS_A and WS_B.
- WS_A uses WS_B.
- They use integrated autenthication on IIS and anonymous acess is disabled.
- I have a asp.net front end that use WS_A.

The workflow is:

- domain\user1 in active directory asp.net frontend.
- asp.net front end invoke WS_A with domain\user2
- WS_A invoke WS_B with domain\user3

The code usede to pass credentials from WS_A to WS_B is:

CredentialCache cache = new CredentialCache();
cache.Add(new Uri(service.Url),

"Negotiate", new
NetworkCredential(strUser,

strPassword, strDomain));
service.Credentials = cache;
service.PreAuthenticate = true;


So far so good, I run the asp.net front end that gets data from WS_A and
WS_A gets data from WS_B, but...it only works int the firts 5 min. after I
make the publish of WS_A and WS_B....

Can anynone help me?

It's the "double hop" problem? There is a solution?

Thank you in advance,
Best regards,
Rui