Problem with read-only files in Windows XP

[jarsulicm]

Having a problem with a few Windows XP Professional systems at one of my sites. Here is some exposition to give you the details:

The server is a standard Windows 2000 server. Not many services running, basically just used for file and printer sharing.

Workstations are all Windows 98 SE except for two, which are Windows XP professionals.

The problem is that whenever there is in attempt to access a file on the server from the XP boxes, the system hangs at random and returns an error message that the file is a read-only file. However, none of the files are marked as read-only on the server. If the system is rebooted, the file MAY open just fine or it may return the same error message. If you are persistant and keep rebooting, the file will open. Any idea what could be causing it and how could I remedy it?