As a result of installing the WorkgroupShare client, the Outlook PST file has changed and it may be necessary to revert to a backup of the Outlook PST file.
When the WorkgroupShare client is installed a backup copy of the Outlook PST file is saved in the following folder
C:Documents and SettingsUserLocal SettingsApplication DataSoftalkWorkgroupShareClientBackups
This would need to be restored into the following folder (unless you have specified a different location for the PST file)
C:Documents and SettingsUserLocal SettingsApplication DataMicrosoftOutlook
Note that any changes made since the backup will be lost.
If there is no backup of the PST file then the client setup program was unable to locate the PST file being used by Outlook.