I have had this lens for four years and yesterday it caused Error 01 on my camera. It will be shipped to Canon Factory Service Center for repair today.
Received email from Canon on 12/22/2010 with an estimate of $203.56 to replace the lens mount.
What was the fix... was it a power diaphram change. I fixed an EFS 17-85 for this fault and now have an EF 24-105 also. Seehttp://www.pbase.com/barry_2718/efs1785mm