Hi
Always copy the file on your harddisk first before you open it
Never open it in the mail.
Maybe they send a link to the file to you instead of the file ?
You can try this
Tools>Options>General uncheck "Ignore other Applications"
Exit Excel and try again
If this doesn't work try to re-register Excel
Close Excel first and
On the Windows Taskbar
1 ) Start>Run "excel.exe /unregserver"(no quotes)>OK.
2) Start>Run "excel.exe /regserver"(no quotes)>OK.
See the space between exe and /regserver
You might have to designate a full path to excel.exe.
In that case Start>Run "C:\yourpath\excel.exe /regserver"(no quotes)>OK.