It don't happen on my end with firefox. I will have to install chrome to test for that. I can't imagen why it would do that. I didn't edit the javascript at all.
Do you have these same problems on the demo located on the Lytebox homepage
http://www.dolem.com/lytebox/
EDIT:
I installed Google Chrome and can not re-produce this error. Nor can I re-produce your error on Firefox.
Did you clear your cache?