PLT 299.100 can't save preferences

When I try to access the preferences menu (under "Edit"), I get the following message:

Error saving preferences: make-directory: cannot make directory \\ccis-windows\net\MyHome\.WIN_PROFILE\Application Data\PLT Scheme\(File exists; errorno=17)

After clicking OK, I then get the preferences panel. If I try to change a preference and click OK, I get the message again.

When exiting DrScheme, I get a warning message saying "Preferences Not Saved; Exit anyway?"