Error saving Xls to NT

From W/95 client with office/97 or office/2000 only on a few workstation, sometimes saving an Xls file on a network resource (a shared filder on a NT4.0 sp5),
keep the error
“Document saved successfully. Cannot reopen the saved document due to lowmemory. Please close the document”. On the web I dont have find any solution or applicable suggestion.
On the workstation there is no memory problem. At the time of the error the workstation are correctly running whith Netbeui, TCP, LLC. On the server many other user are running without problem, and someone on the same shared folder and this with the same authorization of the failing users.

I hope to find solution or help about the cause.