How to stop macros opening read only files?
 

I've set up a standard form (form.xls) that copies certain cells
values, opens up a database file (database.xls), pastes them neatly in
the next avaliable row, saves then closes the database file.

However if someone has database.xls open my macro still opens it,
copies and pretends to save it without actually saving the data.

Basically how can I write a couple of lines that stops the read only
database file being opened?