I have quite a few questions. So many, in fact, I'm going to number them to make it a bit easier for you to answer:
(1) First of all, are you using the latest version of wyUpdate & wyBuild, 1.3.1? (Click Help > About in wyBuild to check). If you aren't, update to latest version, rebuild wyUpdate, and include the latest wyUpdate.exe with your app.
(2) These errors occur when you're installing updates, right? Not when you're building them with wyBuild?
(Any chance you can send a screenshot to firstname.lastname@example.org)
Secondly, I need a bit more information. (3) Does the 'fscommand' directory exist before the update begins? That is, is the directory there when the update is being installed, or is it a directory that needs to be created?
(4) Is 'Access' the name of a file you're trying to execute?
(5) Is there a file named 'fscommand' as well as a folder name 'fscommand'?
(6) What Windows version are your using (XP SP3, Vista SP1, etc.)
(7) What is your user permission level (Guest user, Limited User, Admin user)
(8) Is there any chance that I can have a copy of your app before the update, and have access to your update to try to update to the version that's breaking? This would make it much easier to debug.
P.S. If you need an extension on your trial just ask.