@tig said:

The main reason it can't save is that you/others [e.g. SketchUp] don't have the proper permissions to the change things in that folder.
So... [with Admin powers] look at the destination folder, and select its icon.
Right-Click > Context-Menu > Properties >
Security > Edit...
Ensure it's checked as FULL rights, for ALL those listed...
Apply / OK...

Perhaps a good idea to review your folder permissions ?

Regarding running SketchUp as as Admin...
It might not be enough that you are 'an Admin'.
Select the 'SketchUp.exe' icon in the SketchUp folder and use:
Right-Click > Context-Menu > Properties >
Compatibility > Privilege Pane > Check 'Always run this program as an administrator'.
Apply / OK...

I actually have the Mac version so the menu hierarchy you gave doesn't quite jive but I went in and changed some settings for read & write capabilities under the Sketchup application folder. I haven't tried it yet but, I will soon and then I'll report back if this solved it. Thank you.

@panixia said:

did you check all the writing permission related stuff? or did you try to run sketchup as admin?

I only have one computer running Sketchup and it is always run as admin so that isn't an issue. As far as read/writing preferences, I haven't deliberately gone in and changed anything so I can't say that it is anything less than default. If the default for sketchup is to not allow autosave after a manual save, then it is working perfectly. And if this is the case, how do I change it to make sure that it does autosave after a manual save?

Scenario: Open new drawing. Work for hours. Autosave works fine. Manually save file as a project under my client folder. Step away for lunch. Resume drawing. Error pops up every ten minutes saying that autosave failed to save. Remember to manually save every so often. Get aggravated when pop up occurs every ten minutes. Forget to save for an hour or so. Random Sketchup crash. Only autosave file left is the one from just before the first manual save. Waste day.

What is going on here? This happened to me in Sketchup8, 2014 and now 2015. This is not intermittent. Every time I manually save a new drawing, autosave becomes inoperable. Am I not allowed to move Sketchup files where I want them on my own hard drive (no network)?