Can’t create a new meeting on Outlook 2011 and crash issues

1) It doesn't allow me to create a meeting or an appointment. The button, on the top left side, appears disabled and also the option of creating a meeting on the menu bar. I can create a meeting on OWA, iCal and iPhone/iPad and it syncs well, but I still can't schedule from Outlook.

2) My Outlook is crashing very often and for many different reasons. Sometimes when I acces a folder, when I right-click in a specific message or folder, when I try to create a contact. I rebuilt the identities, following some instructions I found here at the forum and also following Microsoft's official response (http://support.microsoft.com/kb/2360509), but the problems (1 and 2) continued the same.

I have MacBook Pro 13", with OS X Lion with all the latest updates. My Office is also updated, with the version 14.2.0 and the latest installed update 14.2.3.

I use Exchange and this is only the one account configured in Outlook. 

So, does anyone know or have a tip how to solve this problem?

Thanks in advance.

Márcio