Query fails to retrieve data

This is a frustrating bug I am currently encountering in Paradox 5.0
database.
I have a paradox table (file size 130 MB). When I use the following query:
Select * from friskpol where fcode = 160222
it returns correct data as required. 

However, when I use Order By clause to this query as follows:
Select * from friskpol where fcode = 160222 order by fpolsym

It fails to return any record. However if I try repairing the same using
Pack
Table option and then retry, things start working fine. But soon, after a
few
days, someone else re****ts the same issue.

It may be noted that when it does not return the data, it does it almost
instantaneously. As if the lazy database does not want to search the data
at
all! Can someone please help? This issue is giving nightmares to me as
well
as my Project Manager.