I am experiencing the issue said to be fixed by hotfix kb938538:
"You experience slow performance in Excel 2007. This issue occurs if the following conditions are true:
• A chart contains lots of data points."

I have downloaded the hotfix file, but when I try to install it i get the error:
"The expected version of the product was not found on the system"

Any ideas?

I'm running Excel 2007 SP1 on Windows XP SP3.

Thanks,
thirdillusion