Thanks for all your answers.
This is what I've tried. Saving from AI(CS5) to eps (to an older version;AI8)but it didn't work. As soon as I go to Import, Signblazer would shut down, didn't even give me a chance to select a file.
Then I've tried what Jay was recommending. I checked the Preview button (No Preview). Saved my AI file as an eps (kept it in CS5 version!)and guess what, it works! I'm not 100% sure since I have to test it out more, but I believe that was the issue. Thanks Jay! I'll keep you updated.
Does anyone know why it takes so long for Signblazer to open? I remembered in the beginning it was 20 seconds but now I'm at 64 seconds! Is that normal?