Using new Project 2010 feature "Sync to Tasks List" get following message-
Microsoft Project Unable to write information for task "XXX" to SharePoint. Ensure "XXX" contains valid data and try again.
Any ideas on the root cause -what exactly could be wrong with the task data?

I am having the same problem. I sent my project to somebody else and they published without problems. I have no idea why my first task under the summary task always has the error Ensure "task name" contains valid data and try again. Can somebody help

I had the same problem. It occured after I installed Project 2007, so that I could have them side by side. I had to run a Repair on Project 2010 and then reboot. That fixed it for me.

I would also ensure that Project is up to SP-1 plus any other CU's as needed. See:

http://technet.microsoft.com/en-us/office/ee748587

for a list of the latest service packs. cumulative updates.

Julie