Access denied on volume

We are running Corel X6 on three PC's

Since two weeks we get an error when we try to save files. Not always but often.

The error says: "access not possible on volume". (its the englisch translation)
After the error the "save as" window appears and MOSTLY it works if we try to save it on same name.
The Problem occours since we installed Corel Graphics Suite X8 and did the Update to SP1 on 01.07.2016.

If the error occours an empty tmp-file is created.

for example:

5028-crl-886e1d2a-29b0-462f-a627-7a281b0da9fa.tmp
5028-crl-20232c39-07d8-493f-86b5-ef019c992c62.tmp
5436-crl-67fe507f-43bb-41d7-be02-5346b6164e1b.tmp
10012-crl-2df67cd8-7743-4aa5-85ff-137ba50fbaba.tmp

On the  same day the first 4 digits are always the same.

The volume is a NAS and the permisssions are correct. Other Programms dont have problems.

Please help me.


Thank you very mutch and im sorry for my bad englisch.