Shareaza

first of all you need to escape the dot character(by preceding it with a backslash) or shareaza will interpret it as 'any single character' -- that is why you can use .* for 'any number of characters'. secondly, shareaza does not support negated character classes (but it sure would be nice) so it is probably interpreting it as 'starts with' (which would be invalid in your first example, and incorrect in the second as well). I can see why you would want that filter though. I have also tried doing this myself in the past.