Access denied when saving Calc on network drive

I can save a Calc worksheet to my network drive but after I reopen the file, I get "Error saving the document : Access to <\server\folder> was denied. I have Domain Admin rights and creating is not a problem, only saving.

Thanks

Update: The access denied occurs when the file is an MS Office extension such as xlsx or docx. This error does not occur when using ODS extensions. I noticed that the .~lock.test1.xlsx# file disappears after each successful save and the I get the error. Then the file reappears and I am able to save.