Preview - ai.icns

I seem to have created a recurring problem with Preview on my MacBook but cannot remember what I did so don't know how to fix it. Any suggestions would be appreciated.

When Preview opens it opens with a 'document' called ai.icns, at the same time the mouse pointer turns to the colour ball and so the software hangs. The only way I can exit out of Preview is to force quit it from my dock.

If I try to open a pdf and it goes to Preview to open the file, the same thing happens.

Kind regards and Merry Christmas.