WordPress MU

hi
first thanks for the you give in this forum

my problem in with the subdomain , i have installed wordpressMU and every things works fine subdomain too works fine but some time it did not working at all or some work and the other not any suggesstion please ?

sorry for my english

what problem?? not clear...May be you change some code??

no i havent i think that is a dns problem ? right ?
thanks for the replay

Maybe if you told us the domain in question, we could check your DNS setup.