Missing most contacts in Communicator 2007 R2

Everyone at my workplace has Communicator 2007 R2 installed and we all use a
global contact list, which I believe is pulled from our Exchange server.
However, I've noticed that only about 50 of the 160+ employees appear in my
list. For those that do not appear, I can still search by name and find
them, but they do not show up in my list of groups and contacts.

Our IT people have made sure everything is configured correctly and had me
reinstall the latest version, but that didn't change anything, and I think I
am so far the only person that has this issue so there is not much of a
priority to fix it. Does anyone have any suggestions I can try myself or
pass along to IT to try on the server side? I'll also be happy to answer any
questions if you need more info.

Thanks,
Chris