Strange problem with net use command /

Dear all,

i have a vb script that calls the net use command on the IPC,then copies some files from the share drive and then releases the share.
This procedure is executed for a number of hosts (windows 98 & xp pcs).
The Server is a 2003 server (on a domain)
The command in question is:
net use \\10.30.1.54\IPC$ /USER:user pass
The problem is that:
when the net use is executed from the script,then it fails giving an error = 2 about start parameters,on 80% of all execution tries.

When i execute exactly the same command from the command line window it never fails.

What could be it be?

Thank you very much,
Chris