. missing in file extensions

[GoodheadDC]

we have a html page internally which has hyper links to power points on it.

 

In the source code form the page the file all seem fine. filename.ppt

 

but when users view the page and click one of the power points the path has lost its . and changed to a - which then renders the link useless.

 

we use ie 11

 

Also if you click it and do a save as the file it wants to save is the same filename-ppt

 

 

its a very behaviour. Any one else seen this?