Insert the CD, boot to it, and choose the repair mode first. I would run the repair and select all the options. See if this works first.

If it does not, then I would run an SFC (system File Checker) in the recovery console. You can get to this the same way. Boot from the CD, choose repair and do the repairs manually. When you get to the command line, you will need to verify the OS directory and maybe the administrator password (should be blank or what you set it on install). Type 'SFC /now'. This will check the system files.

If all else fails, post back and I will give you manual instructions to replace system files. Please note that this is a last resort and may not be successful.