We have found that users having a mixture of office 2003 and 2007
components installed on their workstations cause strange problems with
IE crashing. Both IE 6 and IE 7 would crash when visiting SP sites and
performing certain operations like downloading a document or just
trying to view a list. The problems showed up when the latest round of
security patches from MS were installed. Running Microsoft Office 2007
Diagnostics tool seemed to correct the problem.