Transactional Replication Snapshot Issues - useful resources to resolve
When you have problems with SQL Server replication where the transactional replication is common case in setting up, eventually you will have problems when the data is growing up and any sudden changes in the ETL will also have affect on replication process.
In this case I would suggest in referring to links http://www.sql-server-performance.com/tips/transactional_replication_p1.aspx for transactional and http://www.sql-server-performance.com/tips/replication_tuning_p1.aspx on generic replication. Also When adding a new transactional publication, SQL Server offers you many options to set for the publication. One of these options is the sync_method. This option lets you specify how the snapshot process works and also the locking behavior for the tables that are being replicated, further recommendations when SQL 2000 & 2005 versions are used - http://www.mssqltips.com/tip.asp?tip=1270 link.