After a lot of additional testing, it seems related to a combination of old data saved in the migrated reports and some rogue unescaped "&" in the query strings (both in comments and in case statements/where clauses). I think it has to be an artifact from the migration process because so far I've been unable to make a new report created in 4.1 fail.
The "worst" original report migrated from 3.1 usually crashes on the second refresh.
- If I make a copy of the report, the same behavior occurs.
- If I make a copy of the report and set all queries to "Custom" (bypass the Universe), the same behavior occurs
- If I make a copy, open the report and purge the data, all but one of the log errors disappears (nothing the user will see) and the report can be refreshed multiple times.
- If I make a copy, open the report and fix the "&"s using custom queries, all of the log errors disappear and the report can be refreshed multiple times. So far at least, the WIPS has not crashed. The reports are still slow, but at least they consistently run.
I checked and see the same errors in 3.1 logs, but that version appears better able to handle them without crashing the WIPS.
I'm going to be building a 4.0 environment this week so will check that as well.