Full Text Index Service Error "Exception Message: Input string was not in a correct format." (4262546)

 Error is logged in Archive Manager Event Log as follows:

Event Type:         Error
Event Source:     Full Text Index Service
Event Category: None
Event ID:             2
Date:                     21/08/2008
Time:                     10:57:53
User:                     N/A
Computer:             Archive01
Description:
[3403156645-881327888-1-0x0] The internal error happened:
There was an unhandled exception in this application

Exception Source:           mscorlib
Exception Type:               System.FormatException
Exception Message:         Input string was not in a correct format.
Exception Target Site: StringToNumber
Date and Time:                 21/08/2008 10:57:53
Machine Name:                   Archive01
IP Address:                       192.168.230.123
Current User:                   Example\Archivemgr_Service
CLR Version:                     2.0.50727.1433
Platform (version):       Win32NT (5.2.3790.131072)
Application Domain:       Archive Full Text Index Service.exe
Assembly Codebase:         file:///C:/Program Files/ArchiveManager/Archive Full Text Index Service.exe
Assembly Fullname:         Archive Full Text Index Service, Version=4.0.5.96, Culture=neutral, PublicKeyToken=null
Assembly Version:           4.0.5.96