Problems with NFS on bl35p servers

[Evgeni Genev]

I have an enclosure with 16 bl35p servers. They mount their root file system over nfs. The operating system on the nfs-server is debian unstable. The operating kernel 2.6.18-3. At the beginning it was impossible to start any of the nfs-clients. As soon as one was started, another had lost the link to the nfs-server. I was told to make a firmware update of the system ROMs and of the ILOs.
The firmware of the system ROMs is from 2007.02.14 and the iLO firmware version is 1.89. The firmware of the NICs is also up-to-date.
Now I'm having 13 running blades, but the other 3 are still having problems. As soon as I restart one of them, that's not running, another loses the link to the nfs-server. Bevor he loses the connection, he issues the text in log.txt.
These 3 blades are in bays 4-6.
I have still not updated the firmware of the power management modules. Is this also necessary? If it isn't, what can it be?
I'm quite sure that the nfs-server is functioning - I've had it running with 16 dl145 and dl385 servers. Without any problems...