This has been going on for almost a year. Bing, and only Bing, intermittently adds a (non-existent) directory when requesting files. Example:
"GET www.example.com/YXNlT/page.html HTTP/1.1" 404 4005 "-" "Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)"
Bing does a full crawl of the 150 page site each and every day getting 150 "200" responses, and also getting 40 to 50 "404" responses for non-existent file paths. Hasn't hurt SERP but getting tired of seeing all these "404" in logs.
Anyone else seeing this from Bing?