Our application uses Asynchronous Pluggable Protocol Handler, and everything appears to work fine for us. However, several of our customers have reported a situation where the IE component brings up a "Do you want to open or save this file" dialog, referring to the name we are generating for our cache file, created in our implementation of DataAvailable(). Can anyone think of any reason why this might occur, on a small number of selected machines? We have not been able to reproduce it here, unfortunately. Any suggestions/ideas very greatly appreciated!! Neil