Hi Andy. In the Desktop Client console (select View-Console to see it) you will see a command similar to:

BC "QLARIUS_CR_20" /FILENAME="C:\Users\rminchin\AppData\Local\Temp\pt47141.html"
Browse Request - Operation completed

What file extension is displayed and what is the default editor for that file type if double click on a file with a similar name?

Do you have anything specific defined in the Desktop Client, Tools->Preferences, Editors dialogue? As long as you haven't the default editor should be called.

I would also note that there are times when the file can be deleted before the browser has time to read the file. The Desktop Client automatically deletes the file shortly after you "Open" a Change Request. You can view the Console window in the Desktop Client and manually rerun the same BC command - if you run it manually, the file won't be automatically deleted by the Desktop Client - this may help you determine if something like a virus scanner or other external factor is involved.

thanks we have resolved the issue for now

The temporary files are being created in the "Users\<user name>\AppData\Local\Temp" folder but for some reason dimensions can't read them from there even though it creates them. So we have changed the windows environment variable TMP to point to a new folder within \AppData and that resolves it for use. The better solution would be for use to change the Dimensions DM_TMP symbol to point elsewhere but we don't have the correct admin rights for that.