21.   But a lack of positive reinforcement can play havoc with self-esteem.

22.   But behind the bureaucratic talk, the ministers are trying to ease a crisis that has played havoc with hundreds of millions of lives.

23.   But holidays, news and weather play havoc with the record.

24.   But that would play havoc with both sides.

25.   But such expectations have long played havoc with the minds, if not the lives, of black and Hispanic residents.

26.   But something powerful enough to destroy hardy anthrax spores plays havoc on less hardy objects.

27.   But time dulled his anger, and he became interested in writing a story about how memory and mental distance could play havoc with a murder investigation.

28.   But the two-week project played havoc with schedules, and the results were mediocre.

29.   But waiving the deadline would play havoc with the administration of income taxes, she said.

30.   But weather conditions can be a challenge for sea-based operations, and saltwater corrosion can play havoc on the rocket or its payload, insiders said.