Illustrator CC 2107 opens once then won't open again

[gphe]

I have recently downloaded Illustrator 2017 on a 7 day trial (this is day 2) - Windows 10
I have opened the program, had a bit of a play with the tools and reset some preferences - workspace colour and scratch disc location ( C:\ my SSD) and additional plugin folder (same as Photoshop).
When I close down, it won't reopen - offers to diagnose the problem and can't find the solution - and doesn't open in SAFE mode is it suggest will happen.

If I uninstall and reinstall it seems to work.  

Can scratch disc location or additional preference folder cause issues ?

Photoshop, InDesign, Lightroom etc all work OK

[Ray Yorkshire · Accepted solution]

try resetting the preferences

https://helpx.adobe.com/illustrator/using/setting-preferences.html

[gphe]

It does seem to be more stable if I leave the default preferences