[CentOS] Kernel 2.6.9-42.0.2.plus.c4 doesn´t boot

Hi,

after upgrading with yum upgrade my server doesn´t boot with kernel 
2.6.9-42.0.2.plus.c4 d. Kernel CentOS-4 x86_64 (2.6.9-34.EL) works just 
fine.
I use 2 HDD as RAID1. Unfortunaly this is a root server so i do not have 
any console output. This is rather disappointing cause i run mission 
critical applications on the server.
I guess the updates should be used with more caution.

Regards,

Christian