I hope I can explain this bug clear. Forgive me my poor English.
When I make a file, the filename likes 'struts.jsp', I request this page in my IE, for example 'http://localhost/struts.jsp', it tells me a 404-error.
Then I changed the name to '123struts.jsp', request again, I got the page.
But if I named the page 'struts123.jsp', it'll give me the 404-error again.
I also tried to change the suffix, like 'struts.html', while it's happened again, even though I changed the name like 'struts.txt'.
This bug has occurred in Struts2.0.0, 2.1.8 and 18.104.22.168.
Of couse, if I do not use the Struts2, this bug disappeared.