I ran into a similar problem with the WoW installer (among others), and I discovered that my issue was caused by my having formatted the system drive as HFS+ Journaled AND Case-Sensitive. This causes problems with many programs, and could be the cause of many other errors (Adobe CS3, Word errors, etc.), if your HD is indeed formatted for case-sensitivity. If your OS X system partition is indeed formatted in this way, you can re-install and recover from a time machine backup in the following manner:
1. Boot into install DVD (kalyway, etc.)
2. Reformat partition as Mac OS Extended (Journaled)
3. Re-install OS X
3. Allow install to complete. Upon first boot, use migration assistant to retrieve your data from your time machine backup.
Hope this helps