Hi,
Thanks for posting here.
You may try testing the network connectivity between clients and server by ping utility and check if any packages losing or time out issue occulted .
Have you deployed any third party antivirus or network relate software on both sides ? if yes please disable and try again.
You may also try booting client computer in safe mode with network and check if this issue persist.
For more information please refer to the link below:
Files on network shares open slowly, open as read-only, or you receive an error message
http://support.microsoft.com/?id=814112
Thanks.
Tiger Li
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