There are two different problems, both of which are related to using Alt+P instead of clicking Print, or entering all the way down through.
 
If you type in the Invoice number, first of all it takes from 1-10 seconds to bring up the Form Name Selection Box. Then, once you've selected, it "Processes...." for a long time - 10-30 seconds - before giving an error: FATAL ERR - File T7SOF.SRC Line: 2477 the array element specified is out of range for this field. If you say OK, it just "Processes...." for ever.
 
If you do a Lookup and choose an Invoice, it prints the Last numerical invoice in the file. This happens to always be the same one for us, as we had a rogue invoice get in somehow one time that is numbered way beyond our normal range.