curl multi mysteriously returns no data at random times

we are using curl multi to make 9 simultaneous connections to 9 datasources to
get some data using xml. this is used to display as a search result for
end-users. So if there are 200 people accessing the site at one time then we
are having 9x200 curl processes.

at a random point without any particular pattern we seem to be getting no
responses coming back from our xml sources. When we checked with our sources
we found they never got any request from us in the first place.

i am a bit lost as to how to go about to tackle this problem. any
ideas/suggestions?

nayeem