Here is what I have found regarding ArcReader crashing when the find tool is clicked. I would also like to add that ArcGIS Desktop was doing the same thing on the machine.
Synopsis of our Problem
The problem PC did not have internet access, but it did have network connectivity. We could successfully launch ArcReader and ArcDesktop. It could see the data stored on a networked drive, and even identify the data. Once we clicked on the Find Tool both programs would not respond...they used 0% of the processor...they were unresponsive to any mouse clicks. We found that we had to wait approximately 15 minutes to get the Find Tool to open. We ruled out users profile, computer, and networking issues.
Solution
After a call to Tech Support I was told that with the release of ESRI 10 software some tools, like the Find Tool, were trying to go to an ESRI service (tasks.arcgisonline.com). Since the machine had no internet connectivity it was hanging up on this step.
Our solution was to edit the HOSTS file in the following directory...
C:\Windows\System32\drivers\etc
We added another entry into the file referring the service ESRI was trying to hit to an internal IP address. After doing this the Find Tool open in less then 1 minute.