Unusual PC lockup

When using Word 2000, the computer locks up when attempting to use the scroll bar on the right. The mouse pointer disappears, and the only key command that will respond is ALT+CTRL+DELETE to restart the computer. This is a brand new computer, less than 3 months old. It is running Windows 98SE with an Intel P3-866MHZ, 512MB SDRAM using two 256MB sticks. It is connected to an internal network server running on NT 4.0. The application is installed and running locally on the user's computer. This error only occurs in Word 2000 and no other Office application. Any suggestions will be greatly appreciated.
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first question did you run a virus scan on the system? Also you may want to try to repairing the office 2000 installation, in the add/remove programs.

This is a clean install of Office and the machine was scanned for viruses.

Does it do this with any word document you open?