Excel view "loses" number/date formatting - excel ends up seeing numbers/dates as text (so wont work in formulas)

1) At some point in the page, one issue ends up spanning multiple excel rows... (merged cells)
2) After that, all the numbers/dates are stored as text, rather than numbers (so they dont work in formulas)

We are using Excel 2002.
With Ppen Office, The spanning problem still seems to happen - but it seems to work ok anyway..

If you log into jira as huline with our data, and go to this filter and export as excel, you will note 2 things:
http://jira.london.echonet/secure/IssueNavigator.jspa?mode=hide&requestId=11786