Vacuum again and again

Hi all,

We have a web application which has 15 tables. Out of these, 7 tables has >
400000 records. The client application automatically connects to Postgres
database (at server) after 1 1/2 hours and performs INCREMENTAL UPLOAD to
server from client.

Prob :
Upload option works fine after VACUUM but after 3-4 days, it starts giving
ERRORs... Again, we have to run VACUUM to solve the prob..

So, now a days, it has become our routine to run VACUUM every day to avoid
ERRORs.. caz, when ERROR shown, it causes bad impression on client.

Is there any parameters setting in DATABASE or anything else we can do
(except VACUUM regularly) ?

Postgres 7.2 on Redhat Linux 7.2


Thanx

Denis