The problem with this is... is that not every one is getting it and its a random event. if anyone can reproduce this on file they need to record this in a SW RX and send it to their VAR. There is not an exact known way to fix this issue.
I did find this in the SW KB, that any of you can find for yourself.
From SW KB:
Question: Why does the error message "Failed to save" appear when saving a file across a network location?
Answer: Here are a few recommendations:
1) Check the location of the SolidWorks journal file. This should be on a local machine rather than on the network.
2) Under Tools->Options->System Options->Backups, set Save Auto recover info every n changes to a higher value. In addition, reduce the number of backups per document to 1.
3) If the location of the backup files is the same as the original file, (Tools->Options->System Options->Backups->Save backup files in the same location as the original is checked), then change it to another location on a local drive.
This can be caused due to a network error too, please check with network administrator.
Its Easy to point fingers, its a lot harder for someone to take the time to work on the issue to help others to help them!
Regards,
Scott Baugh, CSWP
faq731-376