2.6.18-1.2239 soft lockup on CPU#0

[Mihamina Rakotomandimby]

Hi,
I use FC5 on an MSI KT4A-V [1] and an AMD Athlon 2800+ CPU.
Kernel is kernel-2.6.18-1.2239.
When booting, I got a "soft lockup detected on CPU#0".
2.6.15 kernel (the one instaled at install time) works fine.
Would you know an existing bug I could confirm or should I open one?
I already searched, and there are many similar problems.
What to do then?