Hans,
Have you tried adding the keyword "poll" at the end of your "snmp-server host vlan203 xxx.xxx.203.254" command?
According to the command reference
"Specify whether traps, polls, or both are acted upon. Use with these parameters:
trapOnly traps will be sent. This host will not be allowed to poll.
pollTraps will not be sent. This host will be allowed to poll.
The default allows both traps and polls to be acted upon."
So, although polls should be allowed, I would try allowing *only* polls.
What version of code are you using on your 525?
-Bryan