Every user that is currently testing Vista in our organization are all having the same issue with lock ups. It will either happen where:
Right click > Run As Administrator > Then you will get the UAC and click I want to continute > Then you will CTRL+ALT+DEL > then you will enter your credentials (happens to both user id's and smart cards) > At this point the program you attempted to run (IE, Explorer, anything, etc) will not come up and if you lock the screen as a standard user then when you go to unlock it you will just see Welcome and the swirly symbol
Do some successful run as tasks and then lock the computer, come back later and (any time between 2 sec and 2 hours) try to unlock the box by pressing CTRL+ALT+DEL and enter your credentials (happens to both user id's and smart cards), poof!! you will just see Welcome and the swirly symbol
Those are the two senarios. There is nothing higher than an informational in the even logs and there are no failed audits. Where does one go from here?