the text style are changed without my intention and appeared suspicious texts. Details below !!

[G.creative.300]

In the text style ,  there is appeared such a strange letters like {18...}.
I am wondering if my file is infected but i am not sure. 
Because all the files's text style are changed from arial to arial narrow without my intention after i resetted the laptop and installed again the autocad. Can you guys help me with this problem? Thank you !

[pendean]

Not likely it is anything more sinister than you inserted or copy/pasted from an outside file with that in it, or RECOVER/AUDIT command tried to fix something and that is the result.

If you think ALL of your files are infected and/or your system is infected too then turn off your computer, then take it to a computer repair shop and pay them to weed through it all and clean it out.

HTH

[dbroad]

Unfortunately this is, incredibly, by Autodesk design.  Each time you use BEDIT to edit or create a block with a dynamic block parameter, those random text styles are created that use simplex.shx.  Autodesk's intent was that creating a new GUID based name wouldn't interfere with existing text styles.  Wish they would've thought of cleaning them up on exiting the block editor.