I am having the exact same issue on a brand new Intuity Audix LX. I set the time, then a week later it is falling about 10 mins slow.
Its under maintenance of course b/c it is new, they sent 1 guy out and he tried to say it was because I hadnt rebooted the server in 6 months, we did that and of course that didnt fix it.
In the server/pc world its a battery/motherboard issue.
Anyone else have this problem?