Last night I've validated my personal website I have to create for 
informatic lesson at school. 
I looked the rules, learnd the right XHTML syntax etc. and tried it with 
opera, my default browser, and worked perfctly. Today, in the school I 
opened and I seemed - firefox knows that there is a synta that script is 
self-closer tag and end with /> but didn't show my website (or anyithing).

I thought: okay, I could change it. I changed, but didnt work again. The 
whole lesson I could only do searching how can I clear firefox's cache 
(it's impossible from firefox, the only way is deleting the folder).

By the way today I had only 4 courses so in the rest time I could explore 
with my friend, Peter, the secret parts of the building.