Ok so I had to reinstall some software, and kept getting repeated installation failures even after system cleansing, restarts, safe mode, etc. Every time it would say:
"Installation failed due to one or more unresolved issues. Error I-001" followed by "Error: Cannot find installation. Check this program is installed before attempting to install" - LOL?!
Anyway, eventually I figured out that if you delete the following hidden folder, you remove the issue.. It's just InstallShield confusing itsself.
C:/Program Files (x86)/InstallShield Installation Information/ <--- Delete that folder and start the installation again. Problem solved.
Note: This is for Windows Vista/7 64bit.. For 32 bit I assume it will be in "Program Files" instead.
Note 2: In Windows XP it should be C:/Program Files/common/InstallShield Installation Information/ - I found that info online and dont use XP any more so I cannot guarantee it.
If ever you run into a similar problem, this solved them all for me without causing any problems. The folder is simply recreated properly. The folder you delete obviously has some corrupt / invalid data in it.