When I try to export video using the H264, a warning comes up and it reads: "AACA Codec not found". I check the codec folder and there are AAC codec in there. How can I reinstall if that is the problem?
Run the Creative Suite Cleaner Tool, then reinstall from your DVD or use the download:
Also check your system and remove any CoDec packs. The problem is most likely not that the Co_Dec doesn't exist, but that its association has been usurped by garbage liek K-Lite or whatever.
The uninstall is optional and really not necessary. The cleaner tool will erase al linstall information, so it looks liek nothing was ever installed and any files that exist simply be overwritten. If your PPro is part of a suite, you'll have to reinstall the entire suite.