Error 22029 On Maint Jobs

OK this is a new error on me.


I have a SQL server 2000 on Windows Server 2003.


I have setup a Maint plan that backs up the user and system databases
and the transaction Logs on my user databases.


Does optimises and integrity checks on those databases as well.
I am not attempting to repair any minor problems.
I am not performing integrity checks before backing up the database
and transaction logs.


All of the databases that I am doing a transaction log backup on have
recovery mode of full.


When the jobs run they fail instantly with error code 22029.
Sqlmaint.exe failed to run. This was working up until the end of the
day on the Thursday before Good Friday. (last week) The transaction
log backup ran fine at 4:00 PM the same job failed at 8:00 PM. No
changes were made to the server during that time.
Another issue that started at the same time. I have a web page used to
grab data from a text file export and pull it into an AS400. I use
this server to house the DTS packages and stored procedures that the
process needs. I suddenly quit working when the jobs quit running.


We are in a mixed enviroment with most clients on AD and this server
and most others still in a NT 4 domain. We have been like this for at
least 3 months and everything has worked fine. I setup the various
users and systems the way the need to be, to work.


Originally the SQL Agent was running as a generic NT 4 Domain user with
local administrator rights to the local box and server role of system
administrator. The MSSQLSERVER and DTC services were running as the
built in system account.


Everything was happy then it broke.


When I reboot the server the jobs and the website work fine. Then
after a period of time that I have not figured out yet, but more than
15 minutes and less than 2 hours. Everything quits working.


I have changed all the services to run as a domain admin with SQL
system adminsitrator server role. Still same thing.


I have changed all the services to run as the built in system account.
Still same thing.


I run the sqlmaint from command line with the switches that I am using
in the maint jobs and it runs fine.


I have run dbcc checkdb on all the databases and they are fine.


The DTS packages and the stored procedures used by the website run fine
from with in Query analyzer.


Any help you can provide would be greatly appreciated.