If you've used SoftGrid or App-V for any length of time then you're surely aware of the virtual drive letter used by each client to host the virtual applications. Typically this is Q: but can be other drive letters as well. Under normal circumstances the user is unable to access this drive but it still shows up as an available drive and this can cause confusion among users who don't know why it's there and who get error messages when they try to access it. If this is a concern of yours then the solution of course is to simply hide the drive letter so your users don't know it's even there.
This article describes how to hide and to restrict access to the SoftGrid Client drive letter by using Group Policy objects (GPO). The policies can be applied when the sequence is created, is updated, or is started. When you start the policies, you can apply the policies to the virtual registry by modifying the .osd file to import a .reg file or a .vbs file. Alternatively, you can use the <REGISTRY> element.