Able,
Could you post the full output of the following SQL code as it would be most
helpful information in helping you.

use <your_database_name_here>
go
SELECT @@language
SELECT @@version
EXEC sp_help_fulltext_columns
EXEC sp_help <your_FT-enable_table_name_here>
go

You are getting this error because "of" is considered a noise or stop word
that is maintained in the language-specific noise word files under
\FTDATA\SQLServer\Config\noise.* where * is a three-letter code for your
FT-enable column's "Language for Word Breaker". Specifically, noise.enu = US
English and you can edit this file with notepad.exe and remove "of" and
other words and single letters and digits, but leave at least a single
space, if you decide to remove all noise words. Note, you will have to stop
the "Microsoft Search" (MSSearch.exe) service before saving the file and
then run a Full Population on all of your FT Catalog for the change to be
effective.

Note, there is no such version as "SQL Server 2003". Are you perhaps
refereing to SQL Server 2005 (codename Yukon)?
If so, the noise word files are maintained in a different location
(\MSSQL.1\MSSQL\Binn\FTERef) and with different file names, such as
noiseENU.txt for US English. You will also need to stop a different service
MSFTESQL and then run a Full Population. If you are not using SQL Server
2005, could you post the full output of SELECT @@version ?

Thanks,
John