Most of the people don't have the file extensions shown in Windows when they browse their files. Thus if our friend created this file with notepad, chances are that it'll be actually named "plugins.ini
.txt".
Only thing is that the .txt doesn't show
Ensure you have the file extensions displayed.
*edit*
I got your PM, bamboo. Instead of replying to it I'll post in this thread so it can profit to other members who may encounter the same problem in the future.
In order to have Windows display the file extensions, open a file browsing window, and go to the menu Tools->Folder options (the name may be slightly different because I have the french version of Windows XP). You'll get an options window with three tabs. Click on the "display" one (second tab). There you have a list of checkboxes. Down in that list you have a checkbox that says "Hide extensions for known file types" (or something like that). Just uncheck it and click OK. Now all your files should have the right extension displayed, so you can rename them easily and change their extension by hand.