XP & NT4 -slow opening files of NT4 Srvr

60-80 user network – 2 * 2000 server and 1 Nt4 server

My client is suffering exteremely slow opening and loading of excel files from NT4 server. His ,is the olny XP machine on the network – and the only one with this issue – a second XP unit was purchased – same issue. The issue does not always occur, and apparently is okay follwing a re-boot but will re-occur.

SMB signing has beeen disabled on Domain Controller. autodisconnect has been disabled on the NT4 server.

Latest windows updates have been applied.

Any ideas would be appreciated.