Well, what user did you setup Splunk to run as? If you navigate to your list of services in control panel (if you have access to it) you can view what user the splunkd and splunkweb services start as. In this case its likely its configured with admin credentials for remote WMI access or as a service account which is creating objects which you don't have permission to access.
a workaround? Well, its more of a Windows security feature than an error to work around. You will need elevated privileges or the admin user to give you permission to access all of those local directories (although if its a permission issue then as soon as you create new objects you will lose access to them) or change the user account that Splunk runs as through the services menu. If you do change that then bear in mind it won't be able to access the same files you couldn't previously, you'd need to change all the folder and file permissions before restarting Splunk.
