[CentOS] Troubles with CentOS5 and 3ware RAID controller

Folks,

Since approx. a half year I have run two servers with CentOS4, all was
running very stable.

Then I upgraded to CentOS5 (fresh install). The servers are running
quite unstable since the upgrade. The system is freezing after short uptime.

I suspect the driver for the 3ware controller, because I got such error
messages:

3w-xxxx: scsi0: Character ioctl (0x1f) timed out, resetting card.
3w-xxxx: scsi0: Character ioctl (0x1f) timed out, resetting card.
3w-xxxx: scsi0: Character ioctl (0x1f) timed out, resetting card.

(lots of repeats of this messages)

sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: rejecting I/O to offline device
EXT3-fs error (device sda6): ext3_find_entry: reading directory #2 offset 0
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: rejecting I/O to offline device
sd 0:0:0:0: rejecting I/O to offline device

After some time (few hours) the systems are completely freezing, no
display of errors on the console or logs

Here some relevant data of my system:

00:0a.0 RAID bus controller: 3ware Inc 7xxx/8xxx-series PATA/SATA-RAID
(rev 01)
        Subsystem: 3ware Inc 7xxx/8xxx-series PATA/SATA-RAID
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop-
ParErr- Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
        Latency: 32 (2250ns min), Cache Line Size: 32 bytes
        Interrupt: pin A routed to IRQ 185
        Region 0: I/O ports at e100 [size=16]
        Region 1: Memory at fa824000 (32-bit, non-prefetchable) [size=16]
        Region 2: Memory at fa000000 (32-bit, non-prefetchable) [size=8M]
        [virtual] Expansion ROM at 80060000 [disabled] [size=64K]
        Capabilities: [40] Power Management version 1
                Flags: PMEClk- DSI- D1+ D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-

Kernel: 2.6.18-8.1.6.el5

It cannot be a 3ware hardware error, because the controller was
exchanged with the same results afterwards.

Any hints are very welcome.

Thanks,

Luc