I should have fixed those two issues long time ago; I am just too busy and .... lazy.
It seems more and more people and sending me this concern when they are using the trial version. Don't worry, this issue happens ONLY in the tiral version. The reason is, when the trial version wants to output a trademark, it will measure the image size and determine a font size should be used. It is done by starting from a default font size, then minus a certain degree until it can fit in the given image. Unfortunately, when a loaded image is too small, it could beome negative. I also use the font-size as a factor to randomize the trademark position; hence, the value is passed to the random method might have the chance to be smaller than zero. Then ooops, crashes.
It's a bug, I agree, but seems it only happens in the trial version, I never pay too much attention to it. In the next version, I will remember changing it to reduce confusion.
Thanks for many people who have reported it to me. I feel very sorry about that. I decided to publish an entry here to remind me this issue. And I also decided to leave the issue there as a proof I am not lying in this entry (to hide the fact I am too lazy to fix that at this moment 
)