Perhaps reinstall the workstation while logged in as the admin?  When you say attachments, do you mean attached to memos?

Yes, apologies I should have been more clear. The attachments are attached to memos.

Double check there aren't any printers in your printer list that are invalid, not connected, etc.  And I sometimes change the default printer to something else then back again to my real printer.

Sorry for the delayed response! But that did not seem to be the problem. 

Seems to be happening on all of our Windows 10 machines across the company. Specifically with Office 2016. Which right now we only have about 7 or so but all in different buildings and are all hooked up to different printers. Didn't see any invalid printers. 

Any other ideas??

Have you found a resolution or workaround? I have tested this extensively and reported it to Sage.  it seems to be Win 10 build 1809 or 1903.  Win 10 build 1803 seems to work.

Unfortunately never got it resolved. Sage wasn't much help with either.

Had to go with a work around. We used to store our customers special requirements in a word doc's, now we have an external program that converts them to pdfs and then we just point to the pdfs instead of the word doc's, which works.

And then we just instructed our users that anything they attach to a customer memo must be a pdf. 

I would love to know if you come across a solution though. 

Unfortunately never got it resolved. Sage wasn't much help with either.

Had to go with a work around. We used to store our customers special requirements in a word doc's, now we have an external program that converts them to pdfs and then we just point to the pdfs instead of the word doc's, which works.

And then we just instructed our users that anything they attach to a customer memo must be a pdf. 

I would love to know if you come across a solution though. 

Did you open a case with Sage tech support?  I reported this in January 2019 and again last week after noticing it hadn't been resolved in version 6.1. 

I did back in July of 2018. Switching everything to pdf fixed our solution in the short term though and I had to get moving on some other things so we ended up just leaving it alone. 

If time permits, I may actually look back into this issue though. Sorry I can't be more of help at this time though!

I posted in Sage City a few days ago and John Nichols of Sage replied with a terrific workaround. 

https://www.sagecity.com/support_communities/sage100_erp/f/sage-100-core-financial-modules/133536/unable-to-open-an-xlsx-memo-attachment---v6-10-1-win-10-build-1809-or-1903/354796#354796

Hi, As a temporary workaround rename ..\MAS90\Home\xmllite.dll to \MAS90\Home\xmllite.old

A program correction will be included in the 2020 release.

*Caveat*  If the customer has development partner modifications that include the interpreter utilizing XML functionality renaming the file above will cause an error in the development partner functionality.