This is not the first time we have seen this problem. But, since you have elected not to post your two dmesgs, it will be up to you to determine if you're having the same problem.
In the prior case, the cause was hardware bus enumeration when ACPI was used. See post #27 in
http://daemonforums.org/showthread.php?t=2846
If this doesn't match your particular problem, post more information.