iFolder Server 3.7.2 on SLES10SP2i586
iFolder client 3.7.2 on MS Windows XP SP2

I can access the iFolder Server( from any client machine via web browser( and but when I installed iFolder Client 3.7.2 on XP, and try to connect I got the following error

An error was encountered while connecting to the iFolder server.

System.Web.Services.Protocols.SoapException: Server was unable to process request. > System.ArgumentNullException: Key cannot be null.

Parameter name: key

at System.Collections.Hashtable.ContainsKey(Object key)

at Simias.WebState..ctor(String DomainID)

at Simias.DomainServices.DomainAgent.Login(Uri host, String domainID, NetworkCredential networkCredential, Boolean calledRecursive)

at Simias.DomainServices.DomainAgent.Attach(String host, String user, String password)

at Simias.Web.SimiasService.ConnectToDomain(String UserName, String Password, String Host)

End of inner exception stack trace

please help