Try copying the Titanium discs to your hard drive in iso format then run the installer from virtual drives. Sometimes the read speed of the drive during an install may be to much for error correction to overcome but coping the disc at a slower speed may allow your drive to read through the error. If you are able to copy the bad disc to your drive then chances are you will be able to install it.
Doing this will not any violate copyright laws if you legally purchased the game. By law you are allowed to make back up copies of computer software for occasions such as this.
Legal Stuff:
Copyright and Digital Files -
http://www.copyright.gov/help/faq/faq-digital.html
§ 107. Limitations on exclusive rights: Fair use -
http://www.copyright.gov/title17/92chap1.html#107
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