Hi Paul,
Though the newer versions of Excel are suppose to have no limit, I believe Crystal's export driver may still have a limit of about 200,000 rows.
That being said, when you preview the report, can you scroll to the last page or does it hang? If it does hang, run the report again and go to page 59. Make a note of the rows you see and go to Page 60. What you want to do is find the record that may be causing the report to hang and take a look at the raw data. Possibly a corrupted record, NULL, problem with linking to the subreport or an error would be nice.
If the report does work in Crystal, try exporting just the first 59 or 60 pages of data to Excel. Like above, you want to narrow down other the offending record(s) or a limit.
I have run into similar issues with exporting to Excel and just jumping to the last page in Preview may not trigger the error. When you preview the report you should actually scroll to that page.
Thanks,
Brian