well, they replaced your sig and have given you 4 reasons why it might have been removed.
1. Images must not be greater then 500px wide and 175px high
2. Multiple images are allowed but their total size must not exceed 500px wide and 175px high
3. Sigs are subject to post rules: no ****, offensive matter etc
4. Image filesize must not exceed 200kb
so you did something wrong there.
you gotta remember everyone doesnt have dialup, so its a ***** when you have to wait ten minutes for a page to load caus of peoples sigs, only to find out it wasnt the page you were looking for or whatever.