Mixed half and full duplexing

has anyone experienced any issues in a network environment where some of the physical cabling is 10Mbit only (2 pair) and some is 100Mbit, using Cisco catalyst switches set to autonegotiation of duplexing mode, where systems cannot find network mapsor other strange issues? We have a client that does not believe this could cause problems, while I am certain it has something to do with their issues and am looking for supporting documentation.
Thanks for the assistance.

Bob Welsh
MCSE, A+, CCNA