occasional system hangs during yum update in fc6

[Gianluca Cecchi]

It is at least four times that I have a system hang when doing "yum
update" operations.
This happened at least with latest three kernels (from 2747 up to 2798 today).
At a certain point I get infinite entries of this kind in my messages:

Oct 18 21:58:33 tekka kernel: ide: failed opcode was: unknown
Oct 18 21:58:33 tekka kernel: hde: drive not ready for command
Oct 18 21:58:33 tekka kernel: hde: status error: status=0x58 {
DriveReady SeekComplete DataRequest }

and then system hangs.
hde is the dvd drive that is managed by JMicron controller
Oct 18 22:03:01 tekka kernel: Uniform Multi-Platform E-IDE driver Revision: 7.00
alpha2
Oct 18 22:03:01 tekka kernel: ide: Assuming 33MHz system bus speed for PIO modes
; override with idebus=xx
Oct 18 22:03:01 tekka kernel: JMB363: IDE controller at PCI slot 0000:03:00.1
Oct 18 22:03:01 tekka kernel: ACPI: PCI Interrupt 0000:03:00.1[B] -> GSI 17 (lev
el, low) -> IRQ 177
Oct 18 22:03:01 tekka kernel: JMB363: chipset revision 2
Oct 18 22:03:01 tekka kernel: JMB363: 100% native mode on irq 177
Oct 18 22:03:01 tekka kernel:     ide2: BM-DMA at 0xb400-0xb407, BIOS settings:
hde:pio, hdf:pio
Oct 18 22:03:01 tekka kernel:     ide3: BM-DMA at 0xb408-0xb40f, BIOS settings:
hdg:pio, hdh:pio
Oct 18 22:03:01 tekka kernel: hde: ATAPI DVD DUAL 8X4X12, ATAPI CD/DVD-ROM drive
Oct 18 22:03:01 tekka kernel: ide2 at 0xbc00-0xbc07,0xb882 on irq 177
Oct 18 22:03:01 tekka kernel: ide-floppy driver 0.99.newide

Strangely enough, the thing happens only when I have no cd/dvd into the drive.
No problems if for example I compile or use in other ways the pc.
I am tipically in init 5 and so I don't know if I can sysrq or something...
System is fc6 updated to today.
Hints?