Error Refreshing Scheduled Reports

We have been using CR.com for about two months. At first things were fine, then we noticed the report information wasn't up to date even though the date on the report was current.

Of the 4 reports we have scheduled to run everynight, only one gave an error, but none of them have refreshed since the 3rd of the month. The error Error Refreshing Report: Error 0x8004100f, IDispatch error #3599.

I can go into the scheduled task and click Run Now and things seems to work, but the reports take over an hour each to run, I can't do this durning the day. Any thoughts or suggestions would be appreciated.

TIA