Windows 98/Office 97 freezing

We have a Toshiba Tecra 8200 laptop running Win 98 and Office 97.
If you’re in say Excel 97, choose File Open and then click the drop down menu for “Look In” the laptop freezes up with the only way out being a hard poweroff/on.

This is happening regardless of if you’re logged onto the network or not. So even Windows running in local mode gives the problem when the look in drop down is chosen.
I’ve tested in Word 97 and the same problem occurs. Windows Explorer locks up when started as well so I think it could be a Windows based fault rather than Office.

Any ideas?