Hi all, first time poster here... I'm having a *very* frustrating time with Oblivion...

Sorry for the long post, lots of details I needed to include.

A couple months ago (June), I installed my Oblivion Collector's Edition on my new PC. I did this to test the game and see if it would play nice with a Windows 7, 64-bit setup. I was able to play fine, no problems. I gathered up a bunch of mods from TESNexus for when I was ready to really sink my teeth back into the game (I was waiting for the 5th Anniversary Edition), and then un-installed it using the "programs and features" in the control panel without an error message or any other apparent problem.

Fast forward two months later, I've bought the Oblivion: 5th Anniversary Edition, and gave the old copy to a friend of mine. When attempting to install my new copy of the game tonight (freshly opened, the disc is pristine), I get the following error message:

"Unable to find your Oblivion installation. Please reinstall Oblivion."

I've already have read multiple threads on different forums (including this one) and have tried the following to no avail (in the following order, if I remember correctly):

- Force a manual install, instead of using autorun - (didn't work)
- Checked again under the programs and features option of the control panel, Oblivion is not listed there.
- Deleted the Oblivion folder under [...]/my games/Bethesda (I think that was the path) - (didn't work)
- Used CCleaner to clean up the registry (didn't work)
- Manually Deleted all Bethesda/Oblivion registry keys using regedit (they were located under the "local_machine/software/wow6432node/Bethesda" path - there was no folder directly under [...]/software - (still didn't work)
- Rebooted my PC - (still didn't work)
- Disabled all other running programs (still didn't work)

Other info:

I am the only computer user, and am always logged in as Administrator.

Machine specs (in case it matters):

Windows 7 64-bit (only Windows OS that has ever been on this PC)
3.4 GHz Quad-Core AMD CPU
8 GB of Ram
2 TB Hard Drive (plenty of free space)
ATI 6870 Video card (1 GB video ram)

At this point, I have no idea how to further troubleshoot the issue. Any assistance is appreciated.

Try giving the guide in the FAQ a shot:
http://www.gamesas.com/index.php?/topic/561101-unofficial-technical-faq/page__view__findpost__p__8103714

Thanks for the link, I took a look at the guide, and unfortunately, I have already tried every step it mentions to follow and I'm still getting this error message. I forgot to include it when I posted, but I tried the boot in safe mode and install trick, and the error message still persisted.

I'm really beginning to think there is a rogue registry entry for Shivering Isles/KOTN, because in the error message during installation, it mentions in the window title that it is attempting to install those DLC's. But again, it appears to be the correct disc, only media appears on the other disc.

Well... I feel like a complete idiot... probably gonna get a few flames just for admitting this, but I don't want anyone to have to waste their time hunting down a ghost in the machine when there isn't one...

Turns out there are 3 discs with the anniversary edition... (not merely 2 that I stated earlier) one was hidden under all the paper materials that came with the game and I didn't see it. Although I'm clearly a dummy for not being more thorough... it still would have been nice if the error message had stated "Wrong disc. Please insert disc 1." or something to that effect.

I have successfully installed the game now and am able to play apparently without issue (although I quit after meeting the emperor in the jail cell).

My apologies for a needless ghost hunt, thanks again for your replies and attempts to assist me.

No worries. We have all had days like that..... At least it was an easy fix eh?

Enjoy your playing.