A new published, Microsoft Application Virtualization KB article, describes a hotfix package that contains the latest post CU1 hotfixes for Microsoft Application Virtualization 4.5. Note, that this is not a required update but if you are seeing these behaviors in your environment it may be appropriate for you to test and apply this update. 

More info: KB969774 - Hotfix Package 2 for Microsoft Application Virtualization 4.5 Cumulative Update 1: May 2009