Not able to start Splunk on Windows when coldpath is set to a CIFS share

We have configured Splunk 4.2.2 running on Windows Server 2008 R2 with a coldPath pointing to a volume ("cold") hosted on a CIFS network drive.

Contents of indexes.conf : #Volume Definition

[volume:cold]
path = \\sjc-vault\SplunkArchive\splunk01
maxVolumeDataSizeMB = 1000000

################################################################################
# index definitions
################################################################################

[main]
coldPath = volume:cold\defaultdb\colddb
[history]
coldPath = volume:cold\historydb\colddb
[summary]
coldPath = volume:cold\summarydb\colddb
[_internal]
coldPath = volume:cold\_internaldb\colddb
[_audit]
coldPath = volume:cold\audit\colddb
[_thefishbucket]
coldPath = volume:cold\fishbucket\colddb
[_blocksignature]
coldPath = volume:cold\blockSignature\colddb

However, we get errors on startup for every index with a cold path set to the remote network drive:

In handler 'indexes': Unable to load index configuration: In index '_internal': Failed to create directory '\\sjc-vault\SplunkArchive\splunk02\_internaldb\colddb' (Cannot create a file when that file already exists.

We are using a domain account to run splunkd. This account has full rights to the shares and folders, therefore this should not be a permission issue.

Any advice is appreciated!