Vista - Major system problem

My system needed to be re-activated because i accidently had clicked on change product key thinking I could find my windows stastics there.

When I tried to re-activate it i would get an "Error Code 0xC004E003" this ketp re-appearing.

I followed steps on how to fix this(the steps given were from these forums and had something to do with the commard prompt) and now when ever I try to log into a user i get an "Windows must be reinstalled to activate. Insert the windows installation DVD or CD into your computer to begin the reinstallation process"

The major problem here is that i whenever i try to log into a user account i get that reinstall message and cant get into the user and even if i boot up with the CD in it does not auto start. It also does not appear on safe mode.

I've tried to log-in via the other admin account and from safe mode.

I've also tried to make a new admin account via command prompt and safe mode. These have all failed also.

The Major problems are as follows:
Cannot access any user accounts be it guest or admin

The features that i need to reinstall vista are not available in safe mode.

Overall I cant get any further than the screen where you pick which account to log into.

NOTE: I bought the laptop with vista ultimate already installed and did not upgrade it from XP

Any ideas on how to resovle this problem?

You may have to activate by phone.

Activate Vista by Phone

I cant activate it by phone because i cant get into a user account. Any other solutions?

Your going to have to reinstall the os