Messages and errors in /opt/buildforge/log, CRRBF0979I, CRRBF2157I and CRRBFEEEEE

Occationally when I run a new Build Forge project I'm developing, it doesn't run correctly and I see the following Informational and Error messages in the /opt/buildforge/log
Mon 10 Dec 12:32:28 2012: CRRBF0979I: 21364854: System: Recovering lost lock [bf_manifest].
Mon 10 Dec 12:36:53 2012: CRRBF0979I: 21364854: System: Recovering lost lock [bf_manifest].
Mon 10 Dec 12:41:31 2012: CRRBF0979I: 21364854: System: Recovering lost lock [bf_manifest].
Mon 10 Dec 12:41:31 2012: CRRBF2157I: 21364854: ENV: Select of Env record [47A115B0-42C6-11E2-B2C9-833CE3595C9F] failed, data record no longer exists.
Mon 10 Dec 12:41:32 2012: CRRBF2157I: 21364854: ENV: Select of Env record [47A115B0-42C6-11E2-B2C9-833CE3595C9F] failed, data record no longer exists.
DBD::DB2::st execute failed: [IBM][CLI Driver][DB2/AIX64] SQL0530N  The insert or update value of the FOREIGN KEY "BUILD.BF_RESULTS.FK_BF_RESULT1" is not equal to any value of the parent key of the parent table. 
SQLSTATE=23503
Mon 10 Dec 12:41:32 2012: CRRBFEEEEE: 21364854: Database: DBD::DB2::st execute failed: [IBM][CLI Driver][DB2/AIX64] SQL0530N  The insert or update value of the FOREIGN KEY "BUILD.BF_RESULTS.FK_BF_RESULT1" is not equal to any value of the parent key of the parent table.  SQLSTATE=23503

Mon 10 Dec 12:41:38 2012: CRRBF0551I: 21364854: Database: StackTrace from Process id [21364854] called from [
   BuildForge::DB::db2(./PerlApp/BuildForge/DB/db2.pm:65)
   BuildForge::Project::Step(./PerlApp/BuildForge/Project/Step.pm:526)
   BuildForge::Artifact::Project(./PerlApp/BuildForge/Artifact/Project.pm:972)
   BuildForge::Artifact::Build(./PerlApp/BuildForge/Artifact/Build.pm:656)
   BuildForge::Artifact::Build(./PerlApp/BuildForge/Artifact/Build.pm:342)
   main(.bfproject.pl:53)
   main(.bfproject.pl:46)
]
Mon 10 Dec 12:41:38 2012: CRRBF0556I: 21364854: Database: Trying to call [execute] on a non-existant database handle
DBD::DB2::st execute failed: [IBM][CLI Driver][DB2/AIX64] SQL0530N  The insert or update value of the FOREIGN KEY "BUILD.BF_RESULTS.FK_BF_RESULT5" is not equal to any value of the parent key of the parent table. 
SQLSTATE=23503
Mon 10 Dec 12:41:38 2012: CRRBFEEEEE: 21364854: Database: DBD::DB2::st execute failed: [IBM][CLI Driver][DB2/AIX64] SQL0530N  The insert or update value of the FOREIGN KEY "BUILD.BF_RESULTS.FK_BF_RESULT5" is not e
qual to any value of the parent key of the parent table.  SQLSTATE=23503

Mon 10 Dec 12:41:38 2012: CRRBF0551I: 21364854: Database: StackTrace from Process id [21364854] called from [
   BuildForge::DB::db2(./PerlApp/BuildForge/DB/db2.pm:65)
   BuildForge::Project::Step(./PerlApp/BuildForge/Project/Step.pm:526)
   BuildForge::Artifact::Project(./PerlApp/BuildForge/Artifact/Project.pm:972)
   BuildForge::Project::StepCommand::Inline(./PerlApp/BuildForge/Project/StepCommand/Inline.pm:89)
   BuildForge::Project::Step(./PerlApp/BuildForge/Project/Step.pm:621)
   BuildForge::Artifact::Project(./PerlApp/BuildForge/Artifact/Project.pm:972)
   BuildForge::Artifact::Build(./PerlApp/BuildForge/Artifact/Build.pm:656)
]
There are then many more DB2 errors before the project finishes. In the GUI only steps 1 and 14 have step logs.

Any ideas what is causing these errors? Have we got a corrupt DB?

(Sometimes the project runs fine but it's about 50/50 at the moment.)
Jim....