08-23-2008 03:01 AM
Backup first (in case it's damaged and might get worse), the do database repairs as per this ACT! Knowledge Base article - http://tinyurl.com/5cxdxg
If it's still a problem:
What version of ACT! (the full build from Help | About)?
What operating system?
Local database or network?
Does it happen with every contact you try?
Does it happen in the demo database?