computer freezes with nfs

[Belgiumlmde]

Hi,

my lmde is fully uptodate (UP-8).
I am using 64 bit cinnamon edition on dell laptop XPS M1509
I mount an NFS share through fstab with :
192.168.1.x:/Multimedia /mnt/Multimedia nfs defaults,soft 0 0

when I type mount, this is what it says :
192.168.1.x:/Multimedia on /mnt/Multimedia type nfs (rw,relatime,vers=3,rsize=131072,wsize=131072,namlen=255,soft,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.1.x,mountvers=3,mountport=50932,mountproto=udp,local_lock=none,addr=192.168.1.x)
the nfs share is on a Qnap-nas
when I copy large files (starting from +/- 4 gb) from my laptop to this share the laptop freezes. nothing is possible anymore.(only alt+sysrq+riesub)
this happens with wireless and with cable
the same laptop also has ubuntu 10.04 installed on it and there I don't have a problem.
I also have 2 other desktops, one with Mint 15 and the other with Mint 16. They use the same share on the NAS without problems.
any idea's how to solve it?

[Belgiumlmde]

this seems like a dead forum.