Keep asking me to enter the date when I switch it on? I'd say 50% of the time I turn on it (in the last week) it's asked me to put the time and date in, which I've done, then later on I switch it on again and the same thing happens?
change the 2nd small battery in it that deals with the date and time. It's similar to a watch battery. I'm not sure where it is on a 5d, but have a look inside the main battery compartment and there should be a small housing for it.
