For testing, this must not necessarily be a Windows CD, it could be other data discs also. Perhaps a driver install disc or something like that.
What I suspect:
Either the laser needs to be cleaned, or something is messed up with your operating system. Some games install rogue DRM "drivers" which might affect your drive's performance at all. Or you somehow managed to install malware :eek:
If there are any error messages, please report.
You don't have a Linux Live CD (Knoppix, Ubuntu or Mint) at hand?