(Apologies if this is a CS issue after all, but since the game itself is also screwed up I figured it should go here). So I was messing around with the Construction Set as I am fond of doing, building houses and furnishing them, that kind of thing, and my first clue that something was amiss was when I was positioning the door markers on the outside of a house and the CS informed me that it was having trouble loading the land. I looked closer and saw that the textures were bright pink, but I figured they weren't hurting me at the moment and I'd just need to go into the .bsa and extract the texture files and that would be that; I recently had to re-export my body mods, for instance, because they weren't loading right, which I figured was due to WindowsXP and how when a file has been on the system for a while, the file name turns blue but I can't really discern any other difference so I just assumed it means 'this is old.'

I downloaded a couple more mods, extracted them, closed the CS and opened it back up to refresh the poor thing (since after a while, it won't open new dialogue boxes if I mess with it long enough), but this time it stopped loading about midway through and said that something about the form counts was off, did I wish to correct the header? I forget the exact numbers but I remember that the first number was about twice as big as the second one. I didn't know what this was so I hit 'no,' and proceeded to be informed that Cell CheydinhalEastGate already exists at (30,23). I hit yes to keep playing, and was then warned about Error adding a different cell to a worldspace (it didn't specify beyond the FormID), cell will be destroyed. My eyes very large by now, I hit Yes to keep playing again and was promptly buried in a slew of "cannot find" error messages, including many Oblivion gates and Quest topics such as "attack" and "goodbye,' so many in fact that I stopped trying to write them down and just hit "yes to all" so it would stop asking me EVERY TIME if I wanted to continue playing.

So I tried opening the CS once more, and even though I didn't know what the hell I was doing, this time if it asked me if I wanted to correct the header, I hit yes. Got hit by another avalanche of Cannot Find (I hit yes to all) and when the CS finally loaded up, I noticed that my cell view drop-down menu was a lot shorter. All I have, in fact, are Interiors, ICImperialPalace, Tamriel, and TestHaven. The others are completely, totally, 100% gone. The interiors tied to those worldspaces are still there, but there are no door markers to the exterior doors in the Great Chapel of Dibella in Anvil. I tried loading the Cheydinhal Knights of the Thorn Exterior cell, and the CS crashed.

I restarted my computer. Tried loading the CS again. Same result. So I popped in my Oblivion disc and tried to load my last save and investigate manually, and the game crashed the minute the loading bar appeared on my screen. I opened up OMM to make sure my mods were in the right order--putting Knights below my last edited mod--and noticed that Oblivion.esm was at the very bottom of the list (?!) so I moved it all the way back to the top. Tried loading Oblivion again. Same result. And here I am.

So... what the hell happened? What caused it, something I did or just one of those random glitches-for-no-discernible-reasons? And how do I fix it? It's probably going to involve uninstalling and reinstalling Oblivion, isn't it?

Yes.

I was afraid of that.

Okay, I know that I have to delete the Config.ini file after I'm done since I've heard you guys tell other people that, but can I save the massive folders of meshes and textures I've got in my Data folder, maybe hang onto a couple of .esps? Or does it have to be completely and totally started over?

Most of the mods you installed and the esp's you have made will be left on your Hard Drive. The Oblivion uninstaller is very sloppy and leaves meshes, textures, and esp/esm files from mods and DLC in the Oblivion and Oblivion Data Folder. If you have the GOTY remember to install both discs. Your saved games from before you played with the CS are still usable, and they are left alone when the game is uninstalled by the Installshield Wizard.

Okay. I safeguarded a few subfolders of meshes/textures and a couple of .esps just in case, since they're the mods I've been working on so long. Was waiting for somebody to answer that question before I proceeded. The saved games don't really matter that much to me (honestly, I spend more time in the CS than I do in the game) but it would be nice if everything worked again.

Here goes...

I take it this means I'll have to download the patches and such again?

Umm... since there's no uninstaller in the Oblivion/Data folder, I went to my Control Panel and selected Add or Remove Hardware and clicked on Oblivion... and the installer popped up. I don't even have the disc in, but after InstallShield gets ready, it shows me the EULA and then asks me where I want Oblivion installed to. So... overwrite?

YAAAAY! Everything works again!

Sorry for all this freaking out, but I was afraid of massively screwing something up (worse) and losing all the data on my mods. I re-downloaded all the patches and fired up the CS, and I had no error messages whatsoever! The worldspaces are back! Everything's good!