Which Guest OS did you install?
Windows 7 and Centos
Problem not seen in XP but after upgrading from vmtools March to June in XP I always had an unknown drivers that wants to register "Périphérique système de base"
To solve this problem, I uninstalled vmtools from TP march, rebooted XP, installed vmtools from TP June, rebooted xp
No unknown driver after that
(I think it has been caused because I had restored a snapshot already running, I have been warned vmtools may be malfunctionning, I clicked continue, and started the upgrade directly, if this is the cause of the problem then you should not allow to upgrade vmtools if the snapshot restoration was partially done, I probably had to reboot prior to start upgrading vmtools)
I tried with CentOS 6.2 Guest on Win7-64 SP1 host, the issue is not seen.
What's your CentOS version? Can it always be reproduced?