Nope... It's your system you can do whatever you want.
But you posted the question, and the answer is that you are fighting how Mandrake is supposed to work, so to speak.
This is akin to the newbie installing TAR files for programs which are available via URPMI, it's counter productive and tends to break things.
The whole point of Mandrake is to attempt to easy things for the user. As such it employs scripts and programs that have certain expectations as far as configuration files, etc.
If you set things up manually you'll often find that things will be set back to an unexpected state when you run certain applications that trigger the same programs and scripts.
You CAN work around this but in effect a) expect to deal with this yourself, b) you'll have to track down and modify those programs and scripts which try to set things back...
This includes, profiles, startup services, etc.
Also RPM/URPM updates will want to set things back.