Can't believe nobody's posted this yet. I just searched for the word 'crash' and found only two references to Outlook, with only 1 vote each. Maybe this is unique to our environment so if anyone has a suggestion, I'm all ears. But I haven't found one yet so I'm posting here.
We're running a combination of Office 2007/2010 on Windows 7 SP1 x64 systems. The Outlook clients all worked fine, with or without the CRM 4 clients. Then after upgrading to CRM 2011/RU5, we've had nothing but complaints from users who have their Outlook sessions crash at various times throughout the day, without any apparent pattern of usage to begin to isolate the problems.
All we get in the event logs are Outlook app crash errors, event ID 1000 - nothing specific. As soon as we remove the CRM client, no more crashing.
It's pretty important that this work without crashing the client all day - it's deterring users from wanting to use the product.