in autocad 2015 some files are modified at open without user interaction +fatal error

Killing info center works, but does not solve the problem. I got asterisk on 5 of 15 open files which is in comparison better than 10/14 before, but still here...

At least no more infocenter. I'll see about fatal error in a while whether I want it or not

What are you running for an anti-virus program? Have you tried disabling it just to see what happens?

Are you using any custom lisp routines?

Do you have any Microstation objects in your drawings like linetypes or fonts?

Those are all good questions, but no microstation objects and avast is set to avoid dwg and any autocad related exe...

About the microstation objects... none that I know of..

Custom lisp routines?

Trade files with anyone in China recently?

Look at scalelists and layer filters?

Try doing a WBLOCK of everything in a drawing then popping it into a new drawing to see what happens?