shared buffers in 7.4.2

Hi,

In version 7.4.1-3 I was able to set my shared buffers setting in postgresql.conf to 30000.

I have upgraded to 7.4.2-3 and cannot change the setting to anywhere near the same value.

I have set it at 3000 and successfully started the db.  At 4000 postgres will not start.

The sort mem and vacuum_mem settings don't seem to have any problem.

Windows 2000 sp4, 512 MB of RAM.

Thoughts?

Mike