Once I have downloaded a file and put it onto my v800, as soon as I try to set the theme it says
"File corrupt, cannot be used"

Why is this ?

It May be because of a broken download. Try downloading the file again!
If this does not work you should download the Sony Ericsson Themes Creator and try to open the .thm file using it. If it does, have a look at the phone used to open the .thm on the bottom right side of the screen. If it's a different series phone than yours, then probably that's it...

You can find the themes creator here:
http://www.lasyk.net/download/62688/7/-162...tor3.162688.zip

It may be because of a broken download. Try downloading the file again!
If this does not work you should download the Sony Ericsson Themes Creator and try to open the .thm file using it. If it does, have a look at the phone used to open the .thm on the bottom right side of the screen. If it's a different series phone than yours, then probably that's it...

You can find the themes creator here:
http://www.lasyk.net/download/62688/7/-162...tor3.162688.zip