Hi Guys,
Just to let you know that I also faced the same issue. I wanted to update a HP host from v5.1u2 to v5.5u1 and got the same vibs conflicting error.
I was able to update to v.5.5 but I am getting the same error when trying to apply the v5.5u1 after that.
I am not using Vsphere Update Manager so I have to apply the updates by booting CD/USB.
This is definitively because some Broadcom drivers in v5.5u1 are older than those included in v5.5 and even in v5.1u2...
I will try to report this somewhere to hopefully get a 5.5u2 soon...
Regards