No mount of nfs4 partition with kernel 2.6.22-14-generic possible

Binary package hint: linux-image-2.6.22-14-generic

On our chair we mount nfs4 partitions with authorization by Kerberos protocol. With todays updates to the kernel 2.6.22-14 it is no longer possible. I get following output in the console if I activate the verbose option of 'mount':

$ mount /path
mount.nfs4: pinging: prog 100003 vers 4 prot tcp port 2049

And nothing happens, nothing is mounted. If I try to unmount and to mount the partition one more time, my PC freezes completely (even without any reaction to Alt+B+SysReq).

I can observe the following output in dmesg:

[ 159.805249] printing eip:
[ 159.805251] f8bb2d50
[ 159.805253] *pde = 00000000
[ 159.805258] Oops: 0000 [#1]
[ 159.805260] SMP
[ 159.805264] Modules linked in: des cbc blkcipher binfmt_misc rfcomm l2cap bluetooth vboxdrv nfsd exportfs ppdev i915 drm speedstep_lib cpufreq_powersave cpufreq_stats cpufreq_userspace cpufreq_ondemand cpufreq_conservative freq_table video container sbs button dock ac battery ipv6 rpcsec_gss_krb5 auth_rpcgss lp nfs lockd sunrpc snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi parport_pc parport pcspkr snd_seq_midi_event iTCO_wdt iTCO_vendor_support snd_seq snd_timer snd_seq_device snd soundcore snd_page_alloc shpchp pci_hotplug intel_agp i2c_i810 i2c_algo_bit agpgart i2c_core evdev reiserfs usbhid hid sg sr_mod cdrom sd_mod ata_piix floppy e100 mii aic7xxx scsi_transport_spi ata_generic libata scsi_mod ehci_hcd uhci_hcd usbcore thermal processor fan fuse apparmor commoncap
[ 159.805335] CPU: 0
[ 159.805336] EIP: 0060:[<f8bb2d50>] Not tainted VLI
[ 159.805337] EFLAGS: 00010292 (2.6.22-14-generic #1)
[ 159.805366] EIP is at rpc_call_sync+0x10/0xa0 [sunrpc]
[ 159.805369] eax: 2af76086 ebx: dc9a7a00 ecx: 00000000 edx: 00000000
[ 159.805372] esi: fffffffb edi: dd093b9c ebp: dd093b9c esp: dd093b68
[ 159.805375] ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068
[ 159.805378] Process mount.nfs4 (pid: 5610, ti=dd092000 task=eda639f0 task.ti=dd092000)
[ 159.805380] Stack: dd093bac 00000001 eadc5128 dc9a7a00 dd093d1e dd093bac dd093b9c f8ce0ac1
[ 159.805388] 00000000 00000000 00000000 00000000 00000000 f8d06638 dd093d1e dd093b88
[ 159.805395] 00000000 00000000 00000000 eadc5128 dc9a7200 eadc5128 dd093d1e f8cd17b3
[ 159.805402] Call Trace:
[ 159.805421] [<f8ce0ac1>] nfs4_server_capabilities+0x71/0xe0 [nfs]
[ 159.805484] [<f8cd17b3>] nfs4_get_root+0x53/0x260 [nfs]
[ 159.805670] [<f8cd4e71>] nfs4_get_sb+0x291/0x370 [nfs]
[ 159.805805] [<c01824e6>] vfs_kern_mount+0xb6/0x130
[ 159.805837] [<c01825bf>] do_kern_mount+0x3f/0xf0
[ 159.805854] [<c019803b>] do_mount+0x66b/0x740
[ 159.805880] [<c02c0c04>] tcp_v4_send_check+0x44/0xf0
[ 159.805900] [<c02ba869>] tcp_transmit_skb+0x3f9/0x800
[ 159.805906] [<c02782af>] sock_aio_read+0x11f/0x130
[ 159.805924] [<c016d217>] __handle_mm_fault+0x687/0xb00
[ 159.805946] [<c0131ab8>] mod_timer+0x18/0x40
[ 159.805992] [<c02f5e59>] do_page_fault+0x389/0x690
[ 159.806042] [<c02f4352>] error_code+0x72/0x80
[ 159.806067] [<c02f00d8>] clip_constructor+0x8/0xa0
[ 159.806073] [<c01968db>] copy_mount_options+0xab/0x150
[ 159.806100] [<c0198677>] sys_mount+0x77/0xc0
[ 159.806119] [<c01041d2>] sysenter_past_esp+0x6b/0xa9
[ 159.806165] =======================
[ 159.806167] Code: 00 89 04 24 31 c0 c7 44 24 04 ff ff ff ff e8 28 f3 57 c7 83 c4 08 c3 8d 74 26 00 55 57 89 d7 56 89 ca 53 be fb ff ff ff 83 ec 0c <f6> 40 30 20 74 0a 83 c4 0c 89 f0 5b 5e 5f 5d c3 f6 c1 01 75 75
[ 159.806204] EIP: [<f8bb2d50>] rpc_call_sync+0x10/0xa0 [sunrpc] SS:ESP 0068:dd093b68

If I boot the kernel 2.6.20-16-generic everything works fine.

Thanks in advance!