Hey guys and girls,
I'm writing to you, because I'm running out of time a bit, so I can't search for myself, it could be take too much time (yes, I or me and my co-worker are in serious time trouble

.
So here are the facts:
We had to change a local network from /24 to /23 because the company is growing and growing and growing.
Unfortunately, nobody else then the management knows anything about pushing the "businessplan" harder and faster as all the time before. So, we were a little bit surprised, when to order came to install 30 Workspaces (PCs, Laptops, Accesspoints, Networkprinters...) at beginning of Aug 2010. So we're running out of IPs in our local network very much earlier the expected. The original timetable to switch the network is now rescheduled from dec 2010 to 8/1/2010...
We altered the dhcp-server settings. The old range from 192.168.41.1 - 192.168.41.254, Subnetmask 255.255.255.0, network 192.168.41.0/24
The new settings: 192.168.40.1 - 192.168.41.254, Subnetmask 255.255.254.0, network 192.168.40.0/23. Addresses are distributed normally, the internal communication is working fine.
So, here comes my problem.
The gateway interface on ethernet 0/0 has the address 192.168.41.1/24. With this setting, all clients in the 41-network can access the internet. The clients in the 40-network can't access the internet.
We're using a Juniper SSG140
Firmware: 6.1.0r1.0 (Firewall+VPN)
My first plan was changing the the /24 to /23. What then happened was a totally mess, all the client's in the 41-subnet can't access the internet anymore, but all in the 40s can (a handful of machines for testing purpose) and the VPN tunnel breaked down (a crowd with dung fokrs and torches was running to our office..

). After switching back, all worked fine, as before.
One thought is, that this may be a routing problem.
My background: I didn't set up the juniper, but now I have to managed it and I'm still learning.
So, if you have any ideas, links etc. or you may assist me here, it would be very helpful, because I'm running massively out of time.
Thanks to the almighty, allgloriuos, geniuses, allpowerfull, magnificent (blah blah blah...) wisdom of the management for NOT talking to the IT-staff....
So guys, it would be glad if you can supply me with (helpful) information's.
Sincerely,
yours Chris (trying not to became crazy when spotting....

)