When I heard description of this problem for first time, I thinking that the guy make me laughing – LN client version 7 will fall down when opening attachment for viewing (if you open it in external application it’s OK). It was little complicated by fact, that the client was running on Terminal server, but I think it should appear on normal computer as well.
And where was the cause? Of course – access right. Client need to open file keyview.ini in directory C:Program FilesLotusNotesMuiCs (just for Czech version, otherwise it’s in LN program folder) for writing and almost at its end fill in the entry Home=. Just add the write access to this file or put in something intelligent and everything is fine. All of this you can guess from Technote 1223782.