Pls tell me why blocking of database is there suddnely while running the crystal report?

Previously this type of error was not there while running the report but why suddenly ?

PID     BlockingSPID     DatabaseName     Duration (Min)     BlockingStatement     Progaram Name     Login Name     LoginTime     LastBatch     HostName     RowNo     LevelRow     [CPUTime]     [Physical_IO]
114     0     SM7     14     SELECT "PROBSUMMARYM1"."NUMBER", "PROBSUMMARYM1"."OPEN_TIME", "PROBSUMMARYM1"."SUBCATEGORY", "PROBSUMMARYM1"."ASSIGNMENT", "PROBSUMMARYM1"."PROBLEM_STATUS", "CONTCTSM1"."FULL_NAME", "PROBSUMMARYM2"."ZCIRCLE", "PROBSUMMARYM1"."CONTACT_PHONE", "PROBSUMMARYM1"."CONTACT_LOCATION", "PROBSUMMARYM1"."OPENED_BY", "PROBSUMMARYM1"."PRIORITY_CODE", "PROBSUMMARYM2"."LAST_UPDATE", "PROBSUMMARYM1"."RESOLVED_TIME", "PROBSUMMARYM1"."CLOSE_TIME", "PROBSUMMARYM1"."UPDATE_TIME", "PROBSUMMARYM1"."INCIDENT_ID", "PROBSUMMARYM1"."UPDATED_BY", "PROBSUMMARYM1"."ASSIGNEE_NAME", "PROBSUMMARYM1"."PRODUCT_TYPE", "PROBSUMMARYM1"."PROBLEM_TYPE", "PROBSUMMARYM2"."CALL_LOGGING_MODE", "PROBSUMMARYM1"."CLOSED_BY", "PROBSUMMARYM1"."RESOLVED_BY", "PROBSUMMARYM1"."RESOLUTION", "PROBSUMMARYM1"."ACTION" FROM ("SM7"."dbo"."PROBSUMMARYM1" "PROBSUMMARYM1" INNER JOIN "SM7"."dbo"."PROBSUMMARYM2" "PROBSUMMARYM2" ON "PROBSUMMARYM1"."NUMBER"="PROBSUMMARYM2"."NUMBER") INNER JOIN "SM7"."dbo"."CONTCTSM1" "CONTCTSM1" ON "PROBSUMMARYM1"."CONTACT_NAME"="CONTCTSM1"."CONTACT_NAME" WHERE NOT ("CONTCTSM1"."FULL_NAME"='Jennifer Falcon' OR "CONTCTSM1"."FULL_NAME"='Test User' OR "CONTCTSM1"."FULL_NAME"='TEST USER UNITECH' OR "CONTCTSM1"."FULL_NAME"='Test09 Test09') AND NOT ("PROBSUMMARYM1"."OPENED_BY"='Jennifer Falcon' OR "PROBSUMMARYM1"."OPENED_BY"='Sachin Nehra' OR "PROBSUMMARYM1"."OPENED_BY"='Soniya Gupta' OR "PROBSUMMARYM1"."OPENED_BY"='Test User' OR "PROBSUMMARYM1"."OPENED_BY"='TEST USER UNITECH' OR "PROBSUMMARYM1"."OPENED_BY"='Test09 Test09')     Crystal Reports     report     Sep 9 2011 7:36AM     Sep 9 2011 7:36AM     GGN_DT_C800406     1     0     954     0
102     114     SM7     14     (@P1 datetime,@P2 varchar(51),@P3 datetime,@P4 varchar(51),@P5 varchar(51),@P6 varchar(41),@P7 varchar(51),@P8 datetime,@P9 varchar(51),@P10 float,@P1