The query processor ran out of internal resources and could not produce a query plan. This is a rare event and only expected for extremely complex queries or queries that reference a very large num

I handle SQL server for my company now a days after getting the application migrated to SQL server 2008R2 SP2 I am getting below error on a regular basis, Help to brainstorm to put a fix for this error,

"The query processor ran out of internal resources and could not produce a query plan. This is a rare event and only expected for extremely complex queries or queries that reference a very large num"

Please explain how critical is this error to a production system and how does this affect the BAU activity

How to get rid of this completely, Much thanks in advance