My company has twenty people using Outlook 2010 and Exchange 365, and overall things work very well. However, we recently added two new Lenovo laptops to the mix. Both of them have exhibited this problem since day one, despite all of my efforts. I have done the Registry hack (http://support.microsoft.com/kb/2264398), rebuilt the user accounts, and even reinstalled from the recovery partition. Nothing has helped. Both users have to connect via the web client to access email. That gets the job done for one of them, but the other is a project manager who very much needs full Outlook integration. (Oddly, she can't download attachments from the web client in any browser. I presume that is an unrelated issue, but it does make the underlying issue even more critical.)
Is there anything else I can try?