MACs killing our network after file transfer

[rotojon1320]

Hey peeps,
I'm the Network Administrator of this visual effects company that works on movie.
Our network is all GIGABIT
We have a linksys giabit router that connects to a NetGear GS748T switch. All gigabit rated, using cat6 everywhere.

Servers:
Server2003 - Active Directory;DNS - AMD Oprweon 2GHZ, 4GB RAM
Server2003 -Quad core, 8GB ram. Raid storage server- raid5 3.2TB
Linux- Ubuntu - website, email.

Workstations:
15) Windows XP Pro SP3; 3-4 GB Ram. 1gbps NIC, 7300LE GFX
3)Windows Vista - sp- 2-4GB ram, 1gbps NIC
3) Apple I-MAC- 1gbps


Problem: During out day we transfer a lot of big movie files around the network. The speed of data throughput is satisfatory (30-50MBS over the network).
Whats happening is, RIGHT after an I-MAC transferes files to the server, NO windows PC can make use of the network at all. No windows machines can send or get anything from the raid server that the MAC just uploaded to.
It seems that after we power cycle the switch and router we're okay to go again.

Does anyone know if MACs on a Windows network slows it down?
I'm having a hard time figuring out what to do here..

Thanks guys.
Jon

 

[rotojon1320]

To elaborate more on this. We have True crypt setup on the server and workstations.
When the OSX's transfer files to the encrypted drive in server2k3, I, on an XP box can't fetch files from a different folder on that encrypted server drive. Now, I can fetch files located on the C: of that server, this is stumping me..
I think it has to do with encryption..?

 

[rotojon1320]

It now seems that whenever a file is uploaded to the serve2k3's encrypted drive "O:\" (which is 8 500 GB 7200 RPM SATA drives in RAID5) allotting to 3.2TB, I'm unable on ANY operating system to download files FROM the server2k3's "O:\" drive.
Is TrueCrypt slowing us down...probably...What should I doooo!!..11!!!