.NET can't perform I/O under odd Group Policy scenario?

[Johnny Drama]

Hi,

My WinForms-based application occasionally reads/writes data from/to the
user's profile directory. I use the following logic to determine where the
user's profile directory is located:

Environment.GetFolderPath(Environment.SpecialFolde r.ApplicationData) +
@"MyAppName\MyDataFile.dat"

If the child folder "MyAppName" doesn't exist, it is created first.

This logic has worked well for many months and many users. A few days
ago we received a tech support call from a user claiming that my app was
crashing on startup. We determined that the error took place when attempting
to access the data file above.

What makes this particular user unique is that his corporation is using
Group Policy based "file redirection" to send all files in the user's
profile directory to a centralized server. I don't know anything about Group
Policy or "file redirection," but apparently this is all supposed to happen
transparently to the calling program.

When this group policy setting is disabled on his machine, my
application works properly. The user claims that my application is the only
one that exhibits the problem. My app is also happens to be the only .NET
application he's using.

Any recommendations? Any known-issues with writing files to the user's
profile folder with this Group Policy setting enabled?

Thanks bro,

Johnny