vladimir.guerreiro (8/31/2012)
Actually, my ideia of comment here, is to see if anyone already had this crazy problem,
Sure, many times. All with very different causes.
You've described a very common symptom, there's just about no way to identify a cause from that, there are many, many possible reasons
I will try to capture in the next event the times and querys that are running slowly and compare the time of the same querys running when the systems is OK.
Query text at a minimum, execution plan and wait stats are highly desired.
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