You have (or had) snapshot replication?
See this article, specifically the section on replication, and the blog post that it references
http://www.sqlservercentral.com/articles/Transaction+Log/72488/
p.s. The truncateonly option is not valid for log files. It's ignored. Don't shrink log files to 0. Shrink to a sensible size.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability