SQL 6.5 database Error Message help please

i have run a simple query on my database
which is :

select * from TransactionDetails

and it comes back with this error:
Msg 602, Level 21, State 15
Could not find row in Sysindexes for dbid '15', object '204527762',index '0'. Run DBCC CHECKTABLE on Sysindexes.
The SQL Server is terminating this process.

and the rest of my tables within the datase are fine
it says run checktable????????
Please help as i have LTD knowlege with SQL 6.5

I found a bunch @ http://support.microsoft.com

Choose SQL Server as the product, and type in "ERROR 602" and look at the results