Colon in Item ? throws "Error creating file..." when trying to SaveAs DWG ?

I have a larger file that produces an "Error creating file ..." when I try to save it as dwg.

After a lengthly search breaking down the file I found that a ":" colon in an item is causing this.

After deleting the colon in the item text .

I attach a file with the same symbol with and without colons

 Neues 5OG Teil2_2_unten13b2a.dgnNeues 5OG Teil2_2_unten13b2a2.dgn