From time-to-time I get this when a breakpoint is triggered. It looks like stack frames aren't getting saved so I can't step back through the call stack - a real pain. See below for an example

--> #0 BatchProcess.add_failure_record(row_id#Fixnum, test#Struct::Test, message#String,...) 
       at line server/processes/batch.rb:309
Warning: saved frames may be incomplete; compare with caller(0).
(rdb:1) pp caller
["./server/processes/batch.rb:309:in `run_tests'",
 "./server/processes/common/generic_process.rb:219:in `each'",
 "./server/processes/common/generic_process.rb:219:in `run_tests'",
 "./server/processes/common/generic_process.rb:271:in `run_plan'",
 "./server/processes/common/corrections.rb:19:in `each_with_index'",
 "./server/processes/common/generic_process.rb:266:in `each'",
 "./server/processes/common/generic_process.rb:266:in `each_with_index'",
 "./server/processes/common/generic_process.rb:266:in `run_plan'",
 "./server/processes/batch.rb:202:in `run_engine'",
 "/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'",
 "./server/processes/batch.rb:201:in `run_engine'",
 "./server/processes/common/generic_process.rb:88:in `run_dataset'",
 "./server/processes/batch.rb:210:in `run_dataset'",
 "/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'",
 "./server/processes/batch.rb:209:in `run_dataset'",
 "./server/processes/common/generic_process.rb:159:in `run'",
 "./server/processes/common/generic_process.rb:158:in `each'",
 "./server/processes/common/generic_process.rb:158:in `run'",
 "./server/processes/batch.rb:350:in `run'",
 "/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'",
 "./server/processes/batch.rb:349:in `run'",
 "server/processes/test_runs/run_tests.rb:55:in `run_one_process'",
 "server/processes/test_runs/run_tests.rb:81"]

Any ideas on how to stop this happening?