This is dumb. Here is the email I sent to Canon US Support:
I have a Canon 500d and an Eye-Fi X2 PRO card. When I put the card in the camera it will not turn on. I have to pull the camera battery to get it to start once the Eye-fi card is removed.
The website below states you are aware of this and have a fix.
Here is a reply I got from Canon US:
Thank you for contacting Canon product support. We value you as a Canon customer and appreciate the opportunity to assist you. We are sorry to hear that you are having memory card issues with your EOS Rebel XSI.
We have not tested the eyefi cards with the EOS Rebel XSI, nor do we have any kind of policy for fixing any issues with these cards. The eyefi cards will work with our EOS Rebel T1i, T2i, T3, and T3i. We do apologize for any inconvenience this may cause.
Please let us know if we can be of any further assistance with your EOS Rebel XSi.
Thank you for choosing Canon.
Technical Support Representative
The XSi is a 450d. AS you can see in my email I have a 500d.